Here's a nice hike that's fun for anybody; from the family with small kids, to the advanced slickrock junkie. I learned of the Many Pools hike from Joe Braun's web site and from this new book of Zion hikes (which is even sold in the Zion NP Visitor Center).
The hike starts with an unmarked trail leaving the highway and dropping down into a wide canyon.
From there you can explore the canyon, walking as far as you like. As you walk up the slickrock, you'll come across many small pools; hence the name. I hiked this in late May and half the pools were dry. I'm sure all the pools are dry later in the summer.
Some of the pools had tadpoles in them.
Some had frogs. Maybe they're toads. I know nothing about these things.
This is an easy hike.
A little further up, there is a large shaded spot under a rock outcropping. This is a perfect place for a rest and a snack. I marked the approximate location of this with a red circle on the map above.
In the late afternoon there would be much less shade.
If you have more time, you can continue up the canyon. I went far enough to leave the slickrock and found some pleasant shade in the trees. Joe says it's possible to reach the plateau above if you keep going, but I turned around. I'll try that some other day.