You wanted to do in Arizona: Sunset Crater, Walnut Canyon and Wupatki. You might consider staying at Bonito national forest campground at the entrance to Sunset to see all three. It's a beautiful campground - no hookups, flush toilets, no showers. Then you could take Hwy 89 north to Hwy 64 east taking you to Trailer Village at Grand Canyon.
Sunset Crater is gorgeous to see but I wouldn't spend a lot of time at Walnut and Wupatki if you're planning on Mesa Verde. Measa Verde is the tops!
4x4 trails - definitely from Ouray, CO
You have a fantastic trip planned. You'll all have a great time and terrific memories! They're lucky kids. :)
