I went with Huakai a few years ago. Like she said, there really wasn't a lot of people. The few that were there were dressed in-style. It was early though. I wasn't 21 either. It did look like a lot of fun. But remember, if it's not as fun as you thought it would be, you could always walk over to JellyRolls for some piano sing-along. We go every year and there never seems to be anyone that is obviously drunk. Definitely let us know how it goes. I'd be interested in trying the Hall out again.
