The one song that my friends liked at concerts [these are friends who are only familiar with his big hit songs] on first listen was A PAINTER PASSING THROUGH. I think this would be a good one since it is autobiographical and he usually performs it very well. Other two songs that he aces all the time is SHADOWS [his most romantic, IMHO] & RESTLESS [most electic]. But as others stated above, it really doesn't matter - GL is going to be on Letterman!
Dorothea