You can search for your dates on expedia and then call up all the disney resorts. It will show you night by night which nights are sold out. This gives you a general idea. If every night has availabilty at most resorts, this is a good indication the resorts are not near capacity. Remember that for some parts of the year what expedia is showing you is what is left in their inventory -- that is rooms for which they have purchased an option. But it's still a decent proxy.