Creating a desert in Bryce is more difficult because you can't rely on your water to make your scene look cool. We like to work with camera angles, haze, sun/sky settings, and textures to make my scenes really pop. Experiment and have fun!
The River Valley is one of my favorite Bryce landscapes for two reasons:
1.) It amazes me how much you can do with a simple mountain.
2.) Simple changes (like the angle, textures, and sky) make a huge difference in how it looks.
Metacreations Bryce is an interesting 3D terrain-generating application. You can build some beautiful landscapes, create animations, and even import 3D models from other programs.
The Island is probably the most common and most basic landscape that you can create in Bryce. We like to take it a step further and edit the mountain a bit for more realism.