Well, I'm not a lady but a lady friend of mine said she had a really great time at Hedonism II. And she's the type who'd likely be looking for some extra on the side.
Actually, you have a couple threads going. I answered Hedonism II, because it's hot. The Sandals resorts are all-inclusive, but they're like a Disney cruise compared to Hedonism II.
I ended up at a Sandals once (not in Jamaica) meeting up with some friends that were staying there (for non-sexual purposes). It had a really intense swingers vibe for some reason. My bf and I were approached by multiple couples/groups in a single night - to the point that we had to sneak away because it was getting too annoying - and they were still calling our names as we disappeared into the night. They also had a single golf pro at the bar and it was apparent he was fucking everyone's wife/GF and was encouraged to do so. Totally not what I expected the Sandals dynamic to be like. I don't know if it was just a weird night/crowd or if it's standard fare at those resorts.
There are plenty of regular adults-only all-inclusives (Playa del Carmen has a good one that's a 5 min walk into the main town as well) but they aren't swinger-spirited. You'd be on your own finding someone who wants to play, but with the vacation hook-up spirit, that might not be too difficult anyway.