Hung out in Williamsburg, Brooklyn last night, hipster chic central:
1st stop: Zebulon (258 Wythe Ave.) Got there round 10:30, by 11pm packed house, live reggae music, may be tough to talk up girls, spotted a couple of groups of cute girls (mid 20s) this place has has potential. Age range 22-28.
2nd stop: Union Pool (424 Union Ave @ Meeker St)
Great music here, 70s-90s. bar upfront can get loud, music venue in back can get crowded, but the best part is the outdoor patio, very conducive for socializing. Talked up few girls here. Age range 25-35. This will be my on my permanent list when in Williamsburg.
Also, a friend mentioned that there is a cafe in nearby Bushwick filled with 20 somethings and Kings County Bar with burlesque on certain occasions.