I wanted to address some of these questions/concerns since I am an intern at Brown this year. I will say that I am tremendously happy here (it sometimes seems strange since aren't you supposed to be miserable during internship?) - so that will color my response.
I also am going to focus largely on Providence/the social scene since those seem to be the concerns here as you already appreciate the academic scene at Brown.
The residents ARE really nice at Brown. Not only are they nice, but they are smart and thoughtful and interested in the world around them. It was such a relief because it felt so different from the people I was classmates with in medical school. And unlike the insanity of med school stress, the people I know are ambitious and committed but aren't stressed out about it (and therefore aren't contributing to a generalized milieu of anxiety as there was in med school).
Socially, I've also been extremely pleased with people in the residency program. My class is generally very inclusive - whenever they go out, everyone you can think to invite is invited. When people send out evites for parties, the entire class is invited. And there are many friendships between classes as well. Moreover, there's always some people on an "easy" month and so there's lots of social stuff. I'll get called to go dancing on a Wednesday night at 10 pm after I've already done things the previous two nights. So whether or not you want to go out a ton or not, there opportunity is there. I personally go out some and stay home some - and that's totally acceptable. Of course you'll connect more with some people than others, but I like how inclusive people are.
Oh, and regarding holidays away from home. Although I was lucky enough to have both Thanksgiving and Christmas off, I got invites for both here in town. During one ward month, one of the residents really wanted to cook a big Thanksgiving dinner (he was working that day) and so he cooked it that weekend and had people over and then brought a full meal into the people who were on call that weekend. For Christmas, I was already home, but I got a call from another friend who was working over Christmas (I worked over New Year's) that she was hosting people for a celebration on Christmas eve. A bunch of people I know went to Montreal for New Year's. Someone just had a big Valentine's day party at her house (for singles and couples!) etc. But the December break, you get 6 days off either over Christmas or New Year's, so that's plenty of time to go home, even if for a short visit.
I'm an urban kind of girl, and was certainly strongly entertaining living in NYC for residency. I feel very lucky, however, to be living in Providence. There are many pockets of commercial areas (restaurants, stores, etc) other than just Thayer Street. I don't actually go to Thayer that much. What's nice about these little pockets is that you can live close to one and be able to walk there to do errands or go out to eat. That's important to me - I would die living in a "suburb" kind of place where I'd have to drive to anything. I do love having my car for when I want to drive somewhere, get somewhere quickly, and if I want to do a big shopping at the market, for example. Rent here is totally reasonable compared with our salary (which is excellent among programs). Providence *is* a small city, but small city in this case does not equate with lack of things to do. I love the clubs, bars, coffee shops, art galleries, restaurants etc here. And there are plenty of them. I didn't find the city "dead" when students were on break necessarily, because you don't have to live in an area that is populated by students - most of us don't. But it does make it easier to find a place to sit at the coffee shop when they're gone! Also, and this is essential - my commute is NOTHING. 10 minutes max. That's essential when you're maximizing sleep and want to avoid frustration. Overall, I feel very fortunate to live here. Residency (especially internship) is a time you want minimal hassles and maximal fun when you want fun - and Providence makes my life so easy in this way.
You can be invovled with Brown as much or as little as you like. I've gone to lots of lectures there, and go to the Brown gym. You use all of the Brown resources. Someone I know sings with the Brown choir. You are part of the community (you get a faculty/staff ID from Brown) and you can get involved if you want. If you don't, you can remain in the Brown residency world (just in the hospitals).
As for golden weekends, you don't necessarily get them every month. You'll get them during your elective months, geriatrics, neurology (depending) and I think you usually get a couple days off in a row on night float and sometimes you are able to tack your "intern appreciation day" against a weekend day off, and then have two days off in a row. I don't know how other programs do it (I feel like a lot of places didn't have too many golden weekends) but certainly you get more golden weekends after intern year (residents get a golden weekend during each ward month). But anywhere that has figured out how to make things work so there are more golden weekends, please share so we can try to do it at Brown! (Also, the program is open minded to change to try to make things work best for everyone - patients, residents etc).
Go with your gut - wherever that takes you. Submit your list and just sit back. It will be out of your hands, and this is a magical time - the first time in a long time that you can only really live in the *present* - you don't know yet where you'll match, and so just enjoy where you are right now and give yourself a break from planning/worrying about what the future holds!
Also - from talking with my med school friends - no matter where people ended up on their rank order list, they are all very happy. So no matter where you end up, know that you will make it yours and you will be happy.