Paulh: How about something by the Eagles or the Byrds.. very cowboy californian.
Queenie: you need some good road music and if you're looking for Disney, there's Heigh Ho, the Elephant song from Jungle Book and Peter Pan also has one about going to find adventure...
Probably not what you are looking for, but we have a cd of music specially written for the Grand Canyon. I think it is called Music for the Grand Canyon and is quite Native American sounding in parts - really nice.
There is actually a quite famous piece of American classical music called 'Grand Canyon Suite' by Ferde Grofe; it is frequently on CDs with Gershwin's 'Porgy and Bess Symphonic Suite' or Aaron Copland's 'Billy the Kid' and 'Rodeo' suites.