I want to throw my BF a surprise 21st birthday party in downtown San Diego..Wheres a good place?

First off, I am going to be the only under age person (20) so it has to be 18 & over. I am getting a room at the hard rock and want to throw him a small surprise party close by. I wanted to throw it at a club but bottle service is so expensive. I thought about renting a big suite & having a party in there. I need ideas!