well, there's a lot of stuff. will you have bikes? if not you can rent em.
my suggestion would be to sign up for an account on
www.dcfixed.com and start a thread saying the same. i'm john on that board.
for beer, i like the brickskeller (google em, their site sucks but the beer is fantastic). if i'm going to "go out" it's usually in the adams morgan neighborhood. there's so much more though, and i know there are some folks that would be happy to show you around.
cheers!