I do a lot of fishing around the Keys and put together a list of some of my kayak launch spots. Although it would seem the Keys would be a great kayak destination, there really is not a significant amount of users as you would think. Launch locations are also tough because like everywhere else, private property encompasses most accessible areas, and the mangroves cover the rest. These videos cover the area from the Bahia Honda Bridge down to Key West and a separate set of video for just Key West. I haven't made it back up the Keys to do the Upper Keys but hopefully will get around to that soon.
Lower Keys
https://www.youtube.com/watch?v=X6_UDjgJlr8Key West
https://www.youtube.com/watch?v=22fJqXGfNJ4https://www.youtube.com/watch?v=fkTVelVPNak