One of my favorite places! A 'must do' is Broadway(the street). Lots of great little dive bars lined up and down both sides of the road. Really good music from up and coming artists are there...country, rock, blues, all of it. And, while you go from bar to bar there are street performers who are amazingly good too. I was there a couple months ago and stopped to hear a guy play an upright bass on the sidewalk...really good! Stood and listened a long time.
Lots to do but with limited time, thats what I'd pick. Hope you have lots of fun.