Most often (especially at the two clubs here in Ottawa where I record a lot), I'll snag a chair for my UA-5 and JB3 (and flashlight and notepad) and place it next to the mic stand. I'll also use a shelf/ledge or a table if it's available. My least favourite method is on top of my backpack on the floor within the footprint of my mic stand. (My backpack is really just the case I use to bring gear to a show, rather than a gear-bringer and gear-holder during recording.)
I was at a really small (cap. 110) club last week to record Sisters Euclid (one of
Kevin Breit's bands), and the place was so small and packed that all I could find for my gear was the seat of a chair up against the table that the other taper (the band's archivist, and a friend) had reserved and covered with gear and his mic stand (my stand was up against the stage). I stood near it for a while, but being 6' 2" tall, I got asked to move, so I said "screw it", and just sat on the floor right beside the chair. This put me about 4' directly in front of (and even in height with) Kevin's amp, which blared at me, hog-heaven style, all night long.
Aloha,
Brad