A few
For a fun place, I recommend:
Bix. Very good ambiance with often times live music. May be a little out of your price range, though. A little bit more "adult" crowd than "young & hip".
Nopa. Great food, very lively.
Two sister restaurants: Town Hall & Salt House. Good American fare, not too expensive.
Dosa. Very "hip" place for Indian food. Not too expensive and always a fun place.
Delfina. Very good, but very difficult to get into.