We don't have our coop/run quite done yet, but plan to use pine shaving (deep litter) in the coop and once they've eaten the grass in the run (which may take a while, since the plan is they'll be pastured or free-ranging and the run won't be used much), we'll use sand in it. I'm intrigued by the leaves idea too. We have tons of maple and oak trees around. No shortage of leaves...