Hi Caroley
We're off down there in October, only for a couple of days, mind.
I visited the Keys 14 years ago and loved it. Haven't stayed in any of the hotels you're looking at though, but friends stayed at Pelican Cove 7 years ago and said it's great.
They're sooo laid back down there - even more so than the other beach resorts. Traffic can sometimes be a bit of a problem at weekends as a lot of the roads are just two tracks (one for south, one for north) as opposed to most four lane US highways. However, the whole ethos of life down there is to RELAX.
The sea is always warm, too, but there aren't that many "swimming" beaches.