Why would you go to the Cape and use an indoor pool? I can see that it might be useful if the weather is bad, but I don't understand the need to make it a priority. For me the Cape is the long stretches of unspoiled beach, the marshes, the grey shingled houses, I could go on and on.
Because we have always headed for the less populated part of the Cape, talk of resorts, AC, indoor pools etc. describe a Cape that is totally foreign to our experience. It seems to me that if a resort atmosphere is what you are looking for, there are more suitable places to choose from than Cape Cod. With much better facilities and probably less expensive, because there's more competition.