The 20th Century Theater is a really polished well run place with good music and some seriously swank special events. If you're seeing a show, go to Habits before (and after!) then get right up and personal with the musical act. I saw Harry Connick Jr. there years ago and he was just right there! I also have had their food at a private event I attended and it was really surprisingly awesome. It had a definite home cooked feel to it. Don't slum it at the Southgate or Bogarts or the Madison Theater, class it up at the 20th Century.
Pros: Clean, classy, friendly and inviting. Great service, great sound and great access to the acts.
Cons: Smaller venue so they don't get the bigger acts.