are you planning on doing an deep sand bed?
the sand grain size is generally more important for your fish and inverts than for corals. some of the bottom dwelling fish (gobies and blennies) and inverts will fare better with a small sugar sized grain. this is mostly to prevent any damage to their belly when the are skimming along the bottom.
keep in mind, that when you add this sand, you are going to have a LOT of particlate in the water until the bacteria seed the sand. live sand will help a little to cut down on the cloudy-ness. if you use a play sand, rinse it as best you can, but you will still get cloudy water for a while.
have a read...