Well I've been browsing through an interesting site, imagining how some of these places could be used for an absolutely amazing paintball scenario. Some attack and defend, capture the flag, etc. These places are amazing. I'm not sure of the laws of how to use an abandoned place for a commercial purpose, but I have seen scenarios before where an abandoned place was used. Try to imagine playing a big game at some of these places.
I am still drooling.
One of the places to pay special attention to; http://www.abandonedny.com/Grey_Hill_Jail.html
EDIT: Especially take note of how awesome this place would be, it even has two buildings as preset team bases and a central building to fight over; http://www.abandonedny.com/boondocks_state_school.html
EDIT V2; WARNING; there may be some images disturbing to some people. One of the places has pictures of a skeletal dog, I'm not quite sure why.