I only have experience with BTAs. They like to hide their foot. They seem to like rocks that kind of look like donuts, or overhangs where their foot and body (sleeve like thing)is deep in the rock behind them and they are mostly covered except for their head... (I don't know technical terms...)
There are way too many different kinds available for the home aquarium though to answer such a broad question. Beyond that, your tank should be set up at least 6 months and really stable before you consider adding one. They require a lot of lighting for the most part, and some are a lot harder than others to care for, but they are all a little harder than most fish.
If I could make a suggestion... do some research on what you'd like to keep.. Google can help with that, or even take a look at the online retailers to see whats available to help you with what to google. Learn the species and the params, and then with a little bit of knowledge in your back pocket, come back to this question with some more specifics.