The highschool we're using was closed, then bought by a private individual, who in turn rented it out to a band for quite some time, then after they we're done using it as their party house/recording studio he starting looking for other people interested in using it. The Edmonton Police use it for some of their training and there's an indoor archery group that rents the gym so it wasn't really a problem at all for us to get the place. We just need to keep the bb's to a minimum afterwards and if we break anything we pay for it.
Our plan is to do a training day at the beginning where a few of the more real-life experienced people in our club will show the new guys the ropes of stacking up and entering a room, then we'll play for a bit, and at the end everyone's chipping in to help clean up the bb's with push brooms and shopvacs. Easy peasy and fun. And indoors. And cheap.
There is also an abandoned hospital in Edmonton here we were trying to get to use, but I think it's off the radar. It's a very popular place for Indy movies to be shot so it's almost always in use.