Here is a photo above Cascade Falls showing some nice, if small, waterfalls. Note that Cascade Falls is approximately a 3.5 mile (one way) hike. So, 7 miles round trip. Nothing for teenagers (except boredom : ), but a little long for younger children under 9 years of age (obviously, it all depends on the child in question). There are places along the trail where you should watch that younger children don't get too close to the edge. No extreme cliffs, but definitely some high places.
The reason that I don't have a photo of Cascade Falls is because, from what I could see, there is only one really nice place to view the Falls from and it was occupied by some other people. My plan was to stop on the way back down and take a photo. Little did I know : )