You won't regret a Monument Valley drive. I can't imagine a better drive in America.
I remember stopping at a McDonald's in Tuba City when I went through about ten years ago. I don't remember if they had hotels there, but it wasn't a real happenin' place.
If you can make it to the Grand Canyon, you should just do that. Stay in the hotel that's right on the rim and then you'll have a full day there once you get up in the morning. The hotel's not fancy and I think it's a bit expensive, but you're a two-minute walk to the most spectacular view you'll ever see.