Hey ! So I bought your pack and started playing with it. I do like it and think it will work for what I plan to do.
I do have a suggestion that should not take too much effort for you and would make a nice addition : wooden floor. This would make you pack suitable to build tower dungeons for example, and add visual variety to rooms easily.
Hope you'll consider it :)
Other suggestion : wall switch,cupboard (with openable doors).