Some friends of mine are planning a day trip to the Grand Canyon from Las Vegas on Christmas Day. It's a group of four adults and four kids. What would be the best way for them to get to and from the Grand Canyon and how should they go about touring it?? Would it be a better idea to rent a van and do it themselves or to just join one of the bus tours out of Las Vegas? If a bus tour is prefereable, are there any outfits you can recommend?