Just north (like 100yrds) of Key is quietwater beach.. a perfect place to sail out of. You could probably leave your boat there overnight but I would just talk to Kirk and see baout keeping the boat next to his for a weekend... who knows if he would ask for a small fee (coors light?) but if he did it would certainly be very fair.
Juanas is a good place and you can keep your boat next to it for a while... but there ain't no hotel there but there is one right across the bridge on the water (not sure you could keep your boat at that hotel, but it would be easier to keep it the mile away at Juanas). I know of a perfect beach spot/camping spot if you have a HT <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />