Zion was fantastic. It got into the 90's one day, but we doing early hikes, so was not a huge problem. We wanted to do the Narrows, but it was closed due to high water levels. We did Angels Landing, a must do as long as you do not have fear of heights. See photo below. We also did Observation Point, a tough day hike but well worth it. Both hikes you need to get started early to beat the crowds and heat.

Bryce was ok. The area with all the formations is really cool, but you can hike that area in one day. I have heard great things about Arches and plan on hiking there possibly next spring.