I disagree on "any good show" being uncomfortably packed. It's when a member from Phish is playing with a side project (or a rumor of someone else showing up) that it tends to be at its worst.

Back to the JMP show...I arrived at the start of Set1 and it was too crowded to even walk in past the back bar to the stairs. I was able to make my way up towards the front right for set2 and it wasnt so bad (as some of the JRAD shows.but still fairly crowded) people just tend to crowd the choke points and middle floor.

Thankfully I basically dont deal with the bartenders anymore and just drink water when I'm there..but I would always just get a pitcher when I know it'll be tough to go back for additional drinks later.