I just posted a longer post but apparently it didn't go through.
Anyway, I've heard stories about big-time comedians dropping in on clubs just to try out new material, and it's awesome that you were there. Chappelle isn't one of my favorites though, I don't know why I've never gotten into him.
I'd rate Pryor, Murphy, Carlin, and especially Louis C.K. above him. Louis C.K. is the best comedian alive, and possibly the funniest guy of all time, in my opinion.
Still cool to see Chappelle up close though.