My "money is no object" idea for a field is pretty simple. Buy a factory with the machinery inside (The particular building that gave me this idea was a five-story vegetable packaging plant/cannery, with lots of large machinery and catwalks). Steel mesh welded to block confined/dangerous spaces, and various blades removed for safety. There could be multiple games being played on separate floors, or open the stairways and elevators for one huge game. I'd think that having the machinery running, adding noise and motion to the environment, might add to the challenge.
Another idea- a variant of the laser-activated Miles gear that the military used to use for training. Refs watch via CCTV and buzz players when they get hit. There would still be a few refs on the field to enforce safety, of course, but it would make it less likely refs would get hit in the crossfire. (On second thought, this might make it feel too much like laser tag. Opinions?)
Of course, this is completely impractical. Startup capital would be way out of reach, insurance costs would be insane, and safety hazards would be too numerous to mention. But it was a fun idea to play around with.