Betsy will probably provide the most useful perspective for your work, but a bunch of background to our experience occurs to me and I'll try to summarize coherently and I hope in complementary fashion to what she has to say.

I write this from the perspective of MALAYSIA X, and note that each Peace Corps group had its own espirit, a compound of the group's specific assignment, Training experiences, and the mix of personalities. Malaysia X was a "Rural Community Development" group (though there were 9 [female] Med Techs too), and included 13 married couples and 16 single men --a smallish group as Peace Corps went in those days. From quite early in the 3 months of training outside Hilo we knew we were going to Sarawak, and I think it was a group of 36 (of the original 51) that arrived in Kuching in September 1965. I'm not sure how many remained for the full two years --I'd guess it was 20-24.

"Development" meant something very different 45 years ago, in terms both of the ideology we imbibed ("gotong royong" and "elicitation of felt needs" being oft-repeated but, as it turned out, totally irrelevant mantras during training --see WH Goodenough's Cooperation in Change: An Anthropological Approach to Community Development [Russell Sage 1963] for the fullest expression) and of the schemes of the Sarawak government (which included covert agendas for resettlement of people away from the Indonesian border, but which foresaw only dimly the deforestation and dam building of the last 25 years). 

The married couples were "trained" to be 4-H organizers (though only 2 of the group had ever lived on a farm...), but several were assigned to other activities once in Sarawak; Betsy and I were (very fortunately) assigned to be assistants to the manager of the Land Development Scheme at Melugu, about 10 miles from Simanggang (now Bandar Sri Aman), so we had quite a different experience from that of 4-H couples, being under the wing of Arthur Thwaites (http://www.flickr.com/photos/blackmerh/325131609/ ), who had been in Sarawak for more than 12 years, most of it working under the remarkable J.K. Wilson in ulu Kanowit (see Wilson's remarkable Budu: Twenty Years in Sarawak Borneo [Tantallon Press 1969, and illustrated by Arthur Thwaites]). Arthur (known to everyone as 'Apai Kumang') was a stupendous resource --a trained nurse who had set up upriver dispensaries, who spoke Iban fluently, and who had none of the standoffishness often associated with the Brits. He was personally dubious about some aspects of the Government's plans, but was unfailingly sensitive and diplomatic in his dealings with all parties.   

The window of 1964-1968 saw a complete upheaval of the remnants of the pre-Malaysia expatriate community, and thus a very substantial change in the organizational details of government departments: Sarawak-born people took over expat positions and began to pursue their own agendas, and not a few Europeans found themselves persona non grata (in some cases, not a moment too soon... [see Judith Heimann's The Most Offending Soul Alive: Tom Harrisson and His Remarkable Life (U Hawaii Press 1997)]).   

Each town with a complement of PCVs had a distinctive character, including a geography of places to eat and drink and buy necessities, a complicated social hierarchy with remaining British civil servants (and their wives...), and a lively legacy of tales and gossip that continued to evolve as Volunteers arrived and departed. For many, that society was more salient and real than the complexities of operating in Iban or Malay or Chinese communities. The PCVs (and, to a degree, VSO, CUSO and other volunteer types) in Simanggang were our natural primary social group, instrumental in showing us the ropes when we first arrived, and essential in helping one another to interpret the day-to-day puzzles around us. I'm sure that this society of volunteers was replicated in other towns, and served a lot of the same functions: people to eat and drink and talk with, people who could understand us and whom we could understand, people who were NOT our (mostly British) bosses, and not Sarawak people either. A few PCVs escaped that local sodality (and were reknowned for their independence), but most relied on it far more than it seemed appropriate to admit.

Another category of relevant people in 1965-1966 was Commonwealth military personnel, very much in evidence in some parts of Sarawak during the Confrontation with Indonesia. In Simanggang, several PCVs spent quite a lot of time with them, and a mild mutual fascination was pretty clear. Many were of much the same age as the PCVs, and similarly engaged in adventures far from home. NAAFI booze flowed freely.

I can't think of ANY other Peace Corps groups during 1965-67 that included married couples. Most of the groups came as teachers and were an important part of the extension of English medium instruction that the Sarawak government was supporting in the middle and late 1960s. Most of those teachers lived within the organizational structure of secondary schools, and were therefore tied pretty closely to routine. By contrast, the single men in Malaysia X were mostly assigned to Public Works Department and were pretty mobile. I didn't know much about the ummmmm practicalities and ins-and-outs of their lives, except for a few especially close friends. In fact, I didn't know a lot about the practicalities of other married couples' lives either.

We were curiosities for Sarawak folk, and they combined hospitality and friendliness with a very broad range of questions, many of which I'm pretty sure I wasn't linguistically sophisticated enough to decode. Certainly groups of women were especially curious about fertility control, though they'd of course never ask ME... but I can't recall that men ever asked analogous questions. They were pretty used to the incomprehension of orang puteh, so I think they cut us a lot of slack and didn't have any expectation that we'd have understanding beyond that of six-year-olds. They were pretty much right.

It's interesting to reflect that there _seemed_ to be no hostility toward us, no envy or jealousy or politically motivated anger. This is at least partly because 1965-1967 happened to be a fairly quiescent time in Sarawak, before various ethnic, economic and political tensions had developed or been articulated as factionalism or interethnic conflict. The Clandestine Communist Organization was a shadowy presence, felt in the Strategic Hamlets along the Kuching-Serian road, but not relevant to PCVs as far as I know. In fact, almost no PCVs had anything like a sophisticated understanding of the complexities and dynamics of the society (really societies) around us --not even of our own PCV society. For most, it was easy enough to live mostly in English, and to absorb the viewpoints and attitudes of the people most like us, who were in many cases British civil servants and other expats. We weren't particularly aware of that or (for the most part) chagrined by the disconnect from the PCV ideals of cultural sensitivity and identification with "local people" that we also affected. We were young and egalitarian, trusting and optimistic... but enmeshed in organizations and hierarchies (schools, government departments) in which there were games and battles and priorities and dynamics we had no basis for understanding, and no possibility of altering to fit our own rosy and very American views of the world.

In the matter of the language fluency that was a part of the Peace Corps ethos, so much depended on one's assignment: secondary school teachers had almost no chance to learn languages, since they were in schools to BE English speakers. In contrast, the (relatively few) primary school teachers HAD to learn the language of their local community or face extreme isolation (and some found the situation very difficult to cope with). There were some notable exceptions to the general picture of low fluency, including some whose assignments allowed or demanded that they work in local languages (some of the PWD guys) and (very important, but never systematically investigated) the not-insignificant number of PCVs who married Sarawak women (sometimes without PC Kuching's knowledge --and one of the Med Techs in our group married a Chinese doctor) or had less formal liaisons. To a much greater degree than most secondary school teachers, these locally-married PCVs lived and worked in local languages. We were aware of many of these paragons, and perhaps envied their capabilities (I did, anyway). And some of our contemporaries were people with little ear for languages BUT fierce determination to communicate no matter what, and they developed strategies in which they communicated largely through people who somehow comprehended and then paraphrased what they said (fascinating to watch/hear, and often surprisingly effective). 

One thing NOT an issue for married couples was loneliness, which I think afflicted many of the single people more than any of us realized. The married couples could retreat to each other's company and thus had the basis for emotional stability --though I know several of the couples in our group didn't stay married after they left Sarawak. Couples DID tend to operate together ("Se duai", "the two of them"), and indeed it would have seemed strange in the Sarawak context for members of a couple to have independent identities, as they surely could at home in the US.

I've often been asked what our presence did for Sarawak, and I've always responded that it did far more for US than for anybody or anything in Sarawak. I'm sure that some of the teachers were in fact very effective, and I'm just as sure that I had no particular effect myself. I don't think I did anybody any harm, though arguably the Melugu Scheme was a pretty significant dislocation for the lives of several hundred families, and I had some small part in its implementation. In our second year we lived in Kuching and traveled around making films, for Peace Corps and for the Sarawak government. The film we made for Peace Corps training ("The PEMS Supervisor") was meant to give trainees something to inform their imaginations, but I have no evidence that it ever did (or even that it was shown). In any case, I don't think that Primary English Medium Scheme (PEMS) continued in the Department of Education, and so far as I know there were no groups of PCVs trained for that assignment after 1967.

I spent a couple of graduate school years thinking that I'd go back to Sarawak for PhD research, but the realities of the late 1960s and early 1970s sent me off in other directions, and I did the research for my dissertation in Nova Scotia instead. The whole experience of Sarawak was enormously important to my own development, but I can see now that I harbored a vast array of illusions about the place, some of which I should have seen through long before I did. I've continued to read material about Sarawak and lately I've been digitizing photographs from 1965-1967 (http://www.flickr.com/search/?s=int&w=47445802%40N00&q=Sarawak&m=text ), but I won't claim that I've really tried to keep up to date for more than 40 years. I can't imagine going back.

Looking over what's crawled out from under the rocks of memory as I wrote this, I'm struck by the parallels to the revisionist history of Brooke Sarawak (notably JH Walker's Power and Prowess: The Origins of Brooke Kingship in Sarawak [Allen and Unwin 2002], but also CS Godshalk's novel Kalimantaan [Abacus 1999]) which paint a picture very different from the rosy Runciman hagiography, Mora Dickson's A Season in Sarawak [Dobson Books 1962], or the BritLit version portrayed in Somerset Maugham stories. One CAN choose to see the peace Corps in Sarawak as an energetic force for good, America at its most open-handed (the JFK legacy --see RB Textor's Cultural Frontiers of the Peace Corps [MIT Press 1966]), but there are other competing versions that are much less entangled with the mythos of the (early) 1960s, and just as productive to entertain though less uncritical of motivations and accomplishments. I think it would take quite a bit of interviewing to break though into those rather murky waters and reconstruct a less idealistic version of the effects and affects of Peace Corps service. I think that many of my ex-PCV friends from other places (Uganda, Thailand and Cameroon spring to mind most immediately) would have interesting analyses in 45-year retrospect, though I'm not sure just what the audience would be for such rethinking. 

I think it's worthwhile to address the question of effects upon PCVs: what DID Peace Corps service do for those who committed two years of their young lives? The ethos was surely rooted in "Ask not what your country can do for you..." and encouraged a commitment to selfless investment in Service, but the actual motivation was usually more complex, and the effects of PC sevice went far beyond whatever the PCV might have imagined at the time. A two-year absence from one's own culture is likely to be profoundly disorienting, and the 1965-1967 period was surely one of the times of great change in the "youth culture" from which most PCVs came. I've always had the sense that I never gained back those two years, that I "missed" something that I would have been an active participant in. No regrets, none at all, but I'm a profoundly different person for the two year Peace Corps experience, and I think most PCVs would say something of the sort (though they might not see it in terms of something "missed" in American culture). It's a measure of something in this realm that during our graduate school years, returned PCVs spotted each other easily, and sought out each other's company. What they had in common was an episode of expatriation, including experiences that were difficult for those who had not been PCVs to understand, but which could be communicated to people who had analogous experiences. It's an important part of this that many exPCVs see the US very differently (and often more critically) for having had a view from outside. Ultimately that's good for the US, but it wasn't part of the original plan. Betsy suggests that many returned Volunteers have taken on volunteer roles at home, but I don't have any data on that myself.