Every Friday after 5 PM, the Philadelphia Museum of Art hosts a music ensemble at the foot of the grand staircase. The genre of music varies, but jazz is always a staple. You can buy wine and food and sit on the steps or at a table if you are lucky enough to get there early or wealthy enough to reserve one of the few tables available to be reserved ahead of time. During the intermission between the first and second music sets, you can stroll through the art galleries. How cool is that?!?! Art After 5 is free with admission to the museum...or completely free if you are or go with a member.
Chris' Jazz Cafe is a wonderful little hole in the wall place with world class jazz musicians. You can pay to sit up front, but it's so small that a free seat at the bar is almost as good. They serve dinner, and while the food is not bad, there are so many other wonderful places within easy walking distance that I almost never eat there, choosing instead to have drinks (and occasionally dessert) while listening to great jazz.