My boyfriend and I are visiting New York from the UK in early June and would like some advice on bars/clubs to go to?

We would like to go somewhere cool/trendy with a laid back vibe - nowhere too prententious! Somewhere where we can have a few cocktails and party.
It's my boyfriends birthday while we are over there so we would like to go for dinner first then hit some bars - so any suggestons of restaurants would be welcome too!

Many thanks