Some very good thoughts here and can't add too much. I would NOT stay at Virgin River - pretty nice place but some ethics issues; don't need that.
We were to be back in that area right now but had to cancel trip. We love Cap Reef and were going to be there a week again. Hwy 12 - aka Escalante Staircase - is beautiful but I personally would not recommend it for RVers unless they have mountain driving experience - steep grades, curves and severe dropoffs both sides with no shoulder or guard rails ( and people who think their half is out of the middle!). Read about it and make up your own mind.
Been to Best Friends twice - amazing place.
We stay at Thousand Lakes in Torrey - a great place and they have a wonderful gift shop with good, fair prices. We also drove the road along the east side of Cap Reef and it was kinda neat - not many people do it.
Out of Bryce we also like Cedar Breaks and Brian Head.
Enjoy.