All suggestions are great, particularly if budget allows.

Be very mindful of acoustics/sound separation and proper HVAC.

I've been in facilities where the walls of the practice rooms didn't go all the way up beyond the ceiling tiles...sound bleedthrough both between practice rooms and the band hall was really bad.

I've also been in a facility where the module practice rooms (the brand mentioned above) was never properly connected to HVAC, even after a later remodeling project. One side of the band hall was unbearably hot while the other was uncomfortably cold depending on the seasons.

Proper storage, exit access, etc. are great considerations, however if acoustics/sound separation and HVAC aren't done properly you'll always be disappointed.