Hmm ok like I didn't really think of much on theme, but maybe possibly (after you start making a profit on it, of course, because it's got to be expensive!) making your themes in a way that they are portable? Reusable wall skins instead of paint, maybe go costumes or something when you show movies idk XD

And you mentioned a horror themed room - maybe like a mini projector for the side wall that like randomly turns on and BAM GHOSTS/ZOMBIES/SOMETHING