I'd hang some decent but inexpensive omnidirectional mics from the ceiling fairly close to the stacks and stage. That seems to be the go-to plan for most venues. Just don't get mics that are REALLY cheap; make sure it's something with high SPL tolerance and something that sounds good. I'd look to Audio Technica, who make lots of high quality, lowish cost mics. Used AT 853 omnis could be particularly good as they are also small.
I'm in this same position as I'll be hanging some perm. mics in a venue soon as well. The only thing here that is throwing me for a loop is that you suggested omnis, acidjack. I'm surprised by that and I was going to use cards. It's quite a noisy room always filled with talkers and I'd rather not get them in the capture. I'll have the mics up on the ceiling at stack level and not too far from the stacks. Wondering why you think omnis are the way to go? Thanks.
Besides that good omnis are cheaper to get good quality, they don't have to be aimed properly (I know it's a 'permanent' install, but shit happens), and up close they will give a natural, rich room sound. You also don't have to fuss with as many mounts, since you can basically just plug an omni into an XLR and drop it down, hanging by its cable, from the ceiling...voila! For cards, you'll need a mount, maybe an extension pole, a t-bar, etc. The omnis are easy.
Also, as Bryon notes, my experience has been that hanging omnis work well. Unless these shows are really quiet I wouldn't worry about talkers, and even at that, if the omni mic is near the PA, I don't think it'd be that bad still.
That said, if I already had some Busmans lying around, I'd probably use them. I would still consider trying the omni caps first, though.