Hamburger rock is just outside of Canyonlands NP. Kids can have fun climbing on the rocks and the campsite is usually pretty empty. Be sure to bring LOTS of water with you, there isn't any available at a reasonable price without a long drive.

If you drive just past Hamburger Rock, you can do some backpacking down Indian Creek.

I stayed at Spruces a few years ago and absolutely loved it. There is an awesome hike to Dog Lake on the North side of the canyon close to the campground.