We camped at both in mid August. At Bryce we stayed at
which is a commercial park at the entrance to the national park. The national park has several campgrounds and a store in the park that had showers. Rubys was a big nice campground and we had full hookups. It was cool at Bryce since it is up in elevation. This campground is located right at the gate and has several motels, restaurants , gas etc but isn't a town.
At Zion we stayed at commercial park right by the south gate to the park. Had full hookups and the park was on the river. It was called Zion Canyon Campground & Quality Inn in Springdale UT . Its listed in Woodall's. It was hot (100 degrees) during the day at Zion and we need the AC. It did get cool by morning and there were many campers in tents. Zion's campgrounds are also within a mile or so of Springdale. Springdale is a little town and is bigger than the Ruby's community at Bryce's gate.
At both parks we were surrounded by French tourists. Thought we had made a wrong turn and gone to France or Quebec. They were all renting motorhome on the west coast and doing the western national park tour.