I am going to agree with Tom on the route for the most part.
You must go to "Monument Valley." Gouldings has a RV Park at MV. Mexican Hat and Forest Gump Highway is near by, once you see the park.
I would come in across the US like Tom suggests, but I would take 24 to Hanksville, South off of IH 70 and take scenic Highway 12 to Capital Reef and Bryce.
You're going to Loop anyway so no matter what route you pick, Include Highway 12 which runs thru Sunrise, and Kanab Utah. 12 is a very beautiful road.
Bryce is a Beautiful Park! One of my Favorites so far. We did not go to Zion on our trip and there is alot of chatter on how beautiful that park is also, but something about a tunnel and waiting to enter, so we passed, as we went in June 2020.
Scenic Highway 12 is very beautiful. I took my 32' Class C towing my 4 Door jeep Wrangler (51' bumper to bumper) leaving Bryce to Moab/Arches. Scenic Highway 12 is Beautiful Road, not real scary. Peaks out at Sunrise Utah around 9000'. Again the road is safe, but has some steep grades on it. I suggest you, Go For it.
JD