Be aware that Zion in July will likely have triple digit temps (we saw 105 every day in the middle of June). It will be a little cooler up at Bryce due to the increased elevation. If you can live with less than FHU's the best deal is the Watchman CG which is actually in Zion NP. For $18 a night ($9 with a Geezer card), you get 30 amps and there is a nice two lane dump station with water throughout the CG. Some of the sites are actually on the Virgin River.
Watchman is just a few hundred yards from the visitors center and the free trams that run throughout the park. Reservations are a must and can be made up to 6 months in advance. Bryce is an easy day trip as are many of the other CG's and attractions.
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