Good to see some one from my neck of the woods!
If the auditorium has good acoustics I would definitely use some room mics for a really big sound. If the horns are playing as sections (note-wise) I would try micing each section a close stereo spread (freeing up a couple inputs) and then add some ambient mics, say 15-20 feet away (I prefer x-y style) and add just enough room sound at mixdown to add some depth (combination of delayed signal from room mics and natural reverb)
If the room is too boomy or has really long decay times I would stick to your first idea.
Just my opinion of course.
I have recorded rather large Funk / Soul bands but never in a good room.