Good full body suit for keeping warm, with some buoyancy

I live in South Florida and when it starts to get a little cold (60-70) I find it hard to swim my best performance. Even if I get myself mentally psyched I notice I swim slower and have worse form. So in preparation for winter this year I am looking to find a full body suit which can help me keep a bit warmer. A great secondary thing would be for it to have a bit of buoyancy so I could see what an effect it has on my posture and performance. I've looked at a bunch of 'technical' suits online, but there are so many I'm finding it difficult to pick the right one. And the biggest problem I have is that I cannot find any places in South Florida which sell these so I can try one out in person before I buy it. Places like Ron Jon Surf shop have full body suits, but I believe those are more for surfers and I would probably have a hard time swimming properly in them. I swim 2-3 times a week, most of the time in an outdoor chlorine pool, doing mostly freestyle and breaststroke. I don't really need an expensive suit that costs a few hundred dollars to shave off a few seconds, and I don't plan on doing any competitions in the near future (At least the next year or so) - though if the suit I bought was competition-allowed that would be a slight plus. If anyone could give me advice I'd really appreciate it. Also, if I can't find a good local store, has anyone had success with buying a suit online and having it actually fit? Thanks!