I put down approximately 1-2" of sand as my base (over clay substrate) and use wood shavings on top. The chickens laugh at the idea of having a "base" and "top" layer and do with it what they will (including burying their 12" off the ground waterer in shavings). I am a graduate student and do not have time to muck out the run every week, much less every day.
A friend of mine uses straw and has found it difficult to keep dry. Despite frequent rain, I have found myself dealing with many fewer issues after deciding on pine shavings. Ironically, we both end up wondering, "where'd all the poop go?" and bantam cochin connoisseur has nailed it - it dries and falls to dust (compost for my future garden!!!). I have no flies despite the sand.
A friend of mine uses straw and has found it difficult to keep dry. Despite frequent rain, I have found myself dealing with many fewer issues after deciding on pine shavings. Ironically, we both end up wondering, "where'd all the poop go?" and bantam cochin connoisseur has nailed it - it dries and falls to dust (compost for my future garden!!!). I have no flies despite the sand.
Just my two cents after raising birds for twenty-five years. If you have a free source of sand it might be worth it, although that does not count your shoveling time. Otherwise, it cost a little too much and in my experience is not optimal for poultry bedding. I did try sand for quite a while and in the end chose to go back with pine shavings after gaining some experience. I will explain the reason I don't like sand as bedding for chickens. Think about it this way, the purpose of any bedding is to create an environment which will not harbor odors, fly larvae, flies and disease. The key to creating this environment is lower moisture content and that is where sand as a bedding fails. Likely, you will agree that if you stick your hand down into sand you will note it is cooler and slightly moist. The top layer of sand protects the lower layers of sand and holds moisture in. This is one of the problems with using sand as a bedding, not reducing moisture in the bedding. Remembering the purpose of any bedding is to create a dry environment, sand responds in just the opposite way. When bird feces lands on the sand, the sand in effect encases the feces preventing the feces from drying out quickly. Then when the bird steps on this sand encased fece pile it flattens out revealing preserved wet sticky feces which quickly adheres to their feet/feathers. Whereas if the feces had landed on wood shavings, the shavings would have immediately absorbed the moisture from the feces causing the feces to dry out. Using shavings creates a drier environment which reduces the flies, odor and disease possibilites. Some might say, "Well sand is great because you can take a cat litter scoop and scoop the feces out every day." I tried doing that everyday and trust me it gets very old scooping wet sticky poop out daily; I am not a high maintenance kind of guy. In my experience wood shavings do not require constant attendance, wood shavings are more absorbent, expel the moisture and dry the chicken feces out. That is the goal. When poop is dried out then when it is walked on it will turn to dust and disintegrate into the lower levels of the shavings.