Key Largo Resort in the FLA Keys, and as you already know - Marco island.

If you will be content with just a nice hotel with a pretty decent pool; there are certainly others which would cost a lot less in points/dollars. I guess the question is - are you wanting to stay at the resort and enjoy the pool or whatever 100% - or that is only a part of the trip and you would spend time out of the hotel sightseeing, beaching it, or other activities where the property is a little less important?