We're interested in doing a tour of the South Rim of the Grand Canyon by bus. We do not want to rent a car and drive. Does anyone have a suggestion as to what bus-tour company to take? Grand-Adventures gets good reviews, however, it's more expensive and while most people seem to feel going in a small van with a small group is a plus, I don't. I'd prefer a bus where there's a rest room with comfortable seats (Grand Adventures sounds like they use a regular van....I don't think that's comfortable for a 5 hour, one way trip.) Any thoughts or recommendations?