You'll be sent the accomodation pack when your place is confirmed.
OK, here's a college breakdown:
James - fairly central, close to Psychology, Physics and the sports centre, has no bar, not a lot of college spirit, but not negative. Mostly really nice acccomodation, some ensuite, either sharing 8 person flats or 16 person houses.
Alcuin - Slightly out of the way, up the hill behind the library, close to chemistry, medical school, library and social work. Really nice accomodation, almost all ensuite, fair college spirit but because it's a bit out of the way, very quiet.
Goodricke - Very central, close to maths, psychology, physics. Some not very attractive accomodation, few if any ensuite, good college spirit.
Vanbrugh - The most central, close to market square, history. Has the best bar! Average looking accomodation, but some new blocks built that are very nice with ensuite. Good college sprit.
Langwith - Fairly central, close to English. Average looking accomodation, few ensuite. Slightly better spirit than James, but not much. Currently negotiating re-vamping the bar which is verrrry quiet.
Derwent - Slightly out of the way, close to Heslington, not sure which subjects. Amazing college spirit, and hosts the most popular events. Not great looking accomodation, and the centre of most of the kitchen-complaints, but most of this has been sorted.
Halifax - Very out of the way, ten minute walk to campus (which makes more of a difference than you'd think) but good college spirit. Recently closed bar. Has its own mini-supermarket. Some not great accomodation (St Lawrence Court) but otherwise generally fine. Close to Heslington.
Wentworth - Postgraduate accomodation only. But very pretty.
I'm sure people will debate some of this, or be able to add stuff, but this is the general consensus from everyone that I know.