Another tutorial by David and myself is ready on our respective websites: Panorama Caverns. This is almost what you will come up with when following the tut. If you bring in your own ideas, it can only get better.
Now this is something you don't see every day. Very nice composition of textures and ground. There's only one thing - well I don't actually have Bryce 5.5 and I haven't looked at the tutorial yet. Is it possible to make all this with the 5th version of Bryce??