Do you have an idea of what fish and anemones you will be getting down the road? That along with the amount of flow you are going to have in your tank may affect what size grain you choose for your sand. You don't need to get live sand, you can start with 'dead' sand and seed it with sand from another established tank and/or with good live rock. If you do choose to go with live sand, it is worth it to get real live sand and not the commercially bagged "live" sand. If you are going with a deep sand bed then I would recommend starting with at least 50% real live sand - if you are going with a more typical sand bed then it is not as important in my opinion. Of the bagged sands my favorite has been Tropic Eden - if you are looking for a white sand, this is very white and very clean.