Wyck, I'd strongly urge you to keep the speaker wires as far away from your cat5/cat6 cable as you can manage.
Because you have a commercial installation, just ask the cabling guys to run the speaker cable inside properly grounded metal conduit. This is common for current-carrying cables in a commercial environment anyway, and while it's not required for speaker cable it will prevent any sort of interference.
Depending on what problem you're trying to solve, you might also find it helpful to run the cat5/cat6 inside separate properly grounded metal conduits.
Speaker cable is trouble for data cable. Normally I'd give you an answer of the form "just do the best you can and don't worry about it." But that's one thing you really should do more for. It usually carries a decent amount of current, at a wide variety of frequencies, and the spectral content keeps varying.