Mo, too bad you're so far away. You sound like my evil twin

. I can relate to practically everything you said. The first hour or so, the a gig is fun; after that, unless it's one of those magical nights where everything comes together (the groove, the crowd), the rest of the night can be just short of drudgery.
Glad to see someone mention the old master, Hank Jones, arguably one of the most tasteful of all the jazz pianist. There are elements of his solo on Autumn Leaves (w/Miles Davis) in nearly everything I play (on piano). "The man just played so pretty" (Oscar Peterson referring to Nat Cole). I don't agree with you on Billie, though. Although the voice was gone, her later stuff with Peterson and Jazz at the Philharmonic had a poignancy and haunting quality that set the stage for all "stylist" that came later. Matter of taste, I guess. Still, I'm impressed. Along with Capt. Russ, you guys really know your jazz history.
Glad the age thing isn't impacting you too much. I'm starting to wonder about myself. Try this experiment. Start jamming with your arranger, then shut down the volume and keep playing. Turn it back on after a few bars and see if you're still in time. You may be suprised.
chas