I need to experiment with some things like different rock formations, less regular stalactites, and adding some stuff to the tiles to make them a little more like uneven terrain.
For props, it'd be cool to be able to build some 3D stalagmites, maybe a cave pool... Other things like that. But, for kitbashing purposes, I think the tiles and walls have to come first.
Update: Here are a couple pictures of in-progress walls:
These are not at all final (nor are they really what I'm striving for. The wall texture is OK. I've also tried reducing the number of stalactites, and I think that'll help a LOT. There's too much texture on the floor/ceiling though, so I'll have to work on fixing that. Even the wall background is a bit much. I'll play with warping it around to see what effects I can pull off.
I'm just getting started. :)