What should I do with the rooms in my 30 story tower?

I have a tower at my spawn location with 30 floors. 15 above ground and 15 below ground. They are 11x11x3 (13 blocks across counting the walls and 3 spaces between floor and celling). I didn't count the roof but you can get up there as well. I'm building a treasure room attached to the side. This will be underground about 6 floors down.

This leaves a lot of unused rooms that are just sitting empty. What should I put in there? What should I do with them? Any good suggestions?