I'd definitely vote for the Black Cat. You can easily get up close to the acts. The sound system and acoustics are pretty good. Even when a Black Cat show sells out, it's never as annoyingly crowded as a sold-out 9:30 Club show. I also think they've had some of the best acts that have come through DC this year: The Gossip, The Decemberists, TV on the Radio, Stellastar*, The Killers, Mission of Burma, and Beulah, just to name a few of the excellent acts that have played the Black Cat this year. And when you get hot from dancing, you can stand right under the air conditioning vent to cool down. I even like their food!