Through Zion's peak season they require you to park and then use the internal tram system to get around. I love it, some people don't.
I really like the Zion River Resort, but it is in Virgin and a 10+ minute drive to the park. If you stay in Springdale, you can catch an in-town shuttle and leave your PU parked at the CG.
It will be hot in July, so go into the park as early in the day as you can to get the most value out of your visit. Bryce and most of the rest where you plan to visit will be at higher altitudes and be more comfortable.
