Looks like a very ambitious schedule. I noticed you have yourself doing Capitol Reef and Arches on the same day. I presume you've looked at the map and realize that it's going to take you at least 2 1/2 hours just to drive from Capitol Reef to Arches, right? IMO that really shortchanges Capitol Reef. There are some great (short) hikes in Capitol Reef, there is fresh fruit you can pick (depending on season) at the Fruita Campground, there's a very scenic dirt road loop (Cathedral Valley) that will take you the better part of a day if you stop to take pictures, there are the Burr Trail Switchbacks, etc.
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Just my opinion but I've always thought Arches was overrated. Yes, it has lots of arches. There are some amazing formations. But if I never go to Arches again, I won't miss it. Canyonlands was much more interesting to me with better vistas and more off-roading. Capitol Reef on the other hand has a really wide variety of terrain, everything from mountains to desert to crazy high rock formations, it's just incredible. I think because of its location, Capitol Reef tends to be "the one that people just drive through" when they're on their way between Moab and Bryce/Zion, and that's a shame.
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You might consider modifying your schedule a bit, since you have some time in Moab and Arches is located just outside of Moab. Instead of trying to do Capitol Reef and Arches on the same day, spend the day at Capitol Reef and then drive to Moab.
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If you're doing the Route 66 thing, don't forget to stop at Standing On the Corner Park in Winslow, Arizona. When we went there in 2014 I took a picture of my wife standing next to the flat bed Ford that's permanently parked there and then posted it on Facebook with the caption: "My Lord!" :sombrero:
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I don't think I'd want to be in a black vehicle in the middle of Summer in the desert, but you live in Texas so I guess you're used to it?