How does this look now?

Day 1: Columbus, OH to Columbia, MO. 535 miles

Day 2: Columbia, MO to Burlington, CO. 561 miles

Day 3: Burlington to Denver to Grand Junction, CO. 408 miles

Day 4: Grand Junction to Durango to Cortez (decent sized town on the map probably with a few motels to choose from). 215 miles + sidetrips
Can check out Mesa Verde while I'm here if there's time in the afternoon

Day 5: Cortez to Monument Valley View Hotel, 124 miles + sidetrips
Can check out Mexican Hat and Moki Dugway on the way. Also, this gives me time to drive inside the valley. I'll be driving a luxury coupe for this entire trip, it should be able to handle the unpaved terrain of Moki and MV, right? Kind of concerned about rock chips though...

Day 6: Monument Valley to Page to Flagstaff, 260 miles
Want to do Antelope Canyon photography tour, Horseshoe Bend. Anything else I should look at along this route?

Day 7: Loop from Flagstaff to Grand Canyon South Rim to Williams. 220 miles
I've been to Grand Canyon as a kid and from what I remember, we didn't spend close to a full day there since we didn't do much hiking. So I'm tempted to head out to Vegas on Day 7, but I'll listen to your advice. Any brief sidetrips I can make on this day though?

Day 8: Williams to Vegas. 218 miles
Hoover Dam on the way.

Day 9: Vegas to LA