Since you are leaving from Williams. Az which is just west of Flagstaff you might want to consider a deviation to the route. Before beginning your trek you need to check road conditions and road closers.
You might want to take RT89 out of Flagstaff to Page, AZ. They have the most wonderful photographic slot canyons. You will have to take a tour, about $50, because it is on the Navajo Reservation. Well worth the money.
Out of Page take Route 98 to RT 160 to Monument valley. There you can catch RT 191 to see Canyonlands National Park up to Arches National Park in Moab, UT. Both of these parks are stunning. At this point you will be closes to Interstate 70 for the short drive to Grand Junction.
While in Denver if you have time Rocky Mountain National Park is a hour and a half away in Estes Park, Co and also have some stunning wildlife and landscape opportunities. I’ll be in Colorado Springs in 2 weeks and can not wait to spend the weekend at the Rocky Mountain National Park.
If you plan on hitting the National Parks it might be worth purchasing the annual pass to save money. It all depends on how many parks you will go to. Link to the parks is
U.S. National Park Service - Experience Your America from here you can see all the parks and find entrance costs.
Enjoy the trip and be sure to share some of the photos.