Glen Helen is one of my favorite places to go hiking, along with neighboring trails in John Bryan State Park. You will see some waterfalls, rock formations, a pine tree forest and creeks. My only complaint is that the trails are not marked. Take a map of the trails along with you if you don't hike these much.
My 6 and 7-year-old love walking this trial with me. We frequent this trail often because the kids love the uniqueness of the trial and the waterfall! Plus there is a access to the creek bed and they love standing on the rocks looking for little fish.
Mister G. on Glen Helen Multi-Trail Loop
Absolutely love this trail. Best hike in the area.