Costa Rica would be an ideal place, there's some absolutely gorgeous, secluded beaches and isles. It's getting to be wet season, but you're pretty much guaranteed sun until at least mid day.
I have neither a yacht nor a villa, but there's some good places I can reccomend. One would be "Isla Del Coco" which is is a a tropical dream island. There's at least one large catamaran you could rent privately, and I'm sure many other boats, giving your privacy and control.
Anyway good luck.
__________________
.
|