We did a Sunset tour with Navajo Spirit Tours and it was wonderful. We left at 4:30 in open air vehicles (think safari) and toured for about 3 hours. We got geology lessons as well as Navajo history, myths and legends. The ride is bumpy, a bit dusty but FUN! It is bumpy because none of the roads are paved, and you have the opportunity to really go off road. The only other way to see Monument Valley is a “self drive”, but you cannot go on some of the roads that the tour will take you, and you will certainly not get the stories, or if you are luck the chanting or flute playing. It is not cheap, but it is a great and memorable way to see the Valley. And to see all this as the sun is setting is quite a memory maker. I would definitely recommend it.