My master bedroom and bathroom are a light brown/mocha color. When I moved in, I thought the color was perfect for my taste, but over time, I've realized that brown is not a good wall color for me (at least in the master bed/bath, where it is in my house). I'm drawn to earthy colors for bedroom linens and accents, and with the walls brown, I feel like any other brown would be too much brown. Additionally, I've realized that brown is not a soothing color for me in either place; it's humdrum. When I replace my upstairs carpet and flooring next year, I'm putting a lighter, non-brown color on the walls.
Another bed/bath is a very nice, mellow, medium-to-light yellow color. I've received many compliments from guests on the yellow in both places.
Downstairs, I have a medium sage-like green color on many walls that has worked out very well. Designers say that green is relaxing and soothing, and that has been my experience.
In addition to the recommendations provided by others, I've also learned (from HGTV) that the ceiling height, room size, and floor color are important factors to consider when choosing paint colors.
Good luck and have fun!