I cannot say enough good things about our tour through Monument Valley with Navajo Spirit tours. First, I would 100% recommend visiting in the winter. I have been in the summer and it is a completely different experience. The landscape was beautifully covered in snow and the crowds are so much smaller, it feels like you are nearly alone at times.
Our tour guide was Will Cowboy. With so few people in the winter, my husband and I basically had a private tour. Will was an amazing guide. By the end of our tour, I felt like I had learned so much about Navajo history and culture. He told us about the Navajo religious stories related to the valley, his family's history (living there for more than 15 generations!), and much more. He always pointed out where to get the best pictures and took pictures of us at different sites. Kind, funny, knowledgable and easy to talk to. Cannot recommend highly enough!