I'm working on caves now, and I've gotten pretty good results by using inverted symetrical lattices. Create, smooth, invert and then raise the lowest level to crop out the bottom. When turned on it's side in Bryce, this gives very nice cave walls. Just kee adding lattices as far back as you can see. Stalactyes and stalagmites are best made with terrains. Remember that stalactyes are long and thin but there should be a corresponding stalagmite below it.