If you have the ability to let them range, but they are just destroying everything, try this. Our chickens were into EVERYTHING (garden, landscaping, etc.) and I was so fed up (and there was poop everywhere!) So we started letting them range only about 1-2 hours before dusk. With this, they still got out of the coop, but they stuck close by since they knew it would be time to roost pretty soon.
That being said, we don't let them range if we aren't around - they like to visit our entire neighborhood, and neighborhood gardens. Try some of the following....
1. Head of cabbage tied on a string just above head height to entertain them
2. Straw or hay bales that they can scratch through
3. Throw lawn clippings into the run
4. If we have chicks, I take a small cup and chick starter and throw it in so they can scratch at it.
5. A small cup of cat food (not very often) for extra protein for them to peck and scratch at.