Originally Posted by
Midwest Michael
The one thing that really sticks out to me is Holbrook - going from Monument Valley to Holbrook then back to the Grand Canyon seems like a really big detour. That almost doubles the distance.
If the detour is for route 66, I might suggest instead to go from Monument Valley to the North Rim (via Lake Powell and/or Antelope Canyon?), then down to the South Rim, and focus on the section of Route 66 from Williams to Kingman through Peach Springs, on the way to Las Vegas. That section is a lot of what inspired what was depicted in the pixar movie "Cars."
Alternatively, if you're going to stick with your current plan, then it would be a shame to go from the North Rim to Las Vegas without giving yourself some time to see Zion National Park, as you'll basically have to go right through it!
For Colorado, personally, I think Royal Gorge is an overpriced, underwhelming tourist trap. I'd just head straight to Colorado Springs and use that time for Garden of the Gods. Another thought, if you're going to Glenwood Springs just for the hot springs, you could instead look at Ouray Hot Springs, which is already on your route at the start of the Million Dollar highway.
The only other thing I would say is that despite me offering some additional suggestions, I'll say your trip is pretty full. There's no single day that is a problem, but on the whole, you might want to be careful that you're not pushing yourself too hard.