Hope you can score the bigger rooms.

Not sure if this was in the links from my earlier, but if you can configure a room, the perfect theater is wider at the screen end than in back, and the floor rises in the back to make it shorter, as well. This has both sonic and visual benefits for the room. An overhead view would look like a partially open folding fan.

While you'd think this would be a reconstruction job, I've known a guy who put progressively deeper "columns" along the walls front to back (in 1st order reflection areas). Also enclosed the equipment closet in one back corner, and enclosed an entry foyer in the other. Really made a difference - but it's still some work.

Also knew someone who had his wife "upholster" some plywood sheeting and hung it on the wall to deaden reflections, a very cheap and easy way to improve the area.