The problem you are going to encounter is that most resorts and cruise ships have a very strict policy about employees having sex with guests. If you do play with someone at Sandals they are taking a huge risk of being fired. We were on a Celebrity cruise where two crew members were fired and dropped of on an island in the middle of no where for having sex with two female passengers. I was shocked at how little the girls cared about the guys loosing their jobs. I won't attempt to seduce the staff for that reason.
Secondly getting your wife hit on at a major resort is somewhat unlikely. It's a huge risk for the staff. How do they know you are looking for something different? I case you hadn't seen them headlines we live in a nation with a very large number of Karen's! Hit on the wrong girl, she goes into Whiney Bitch Mode and you are no longer employees.
I agree with the suggestion to go to Hedonism. Hedonism is a 24 hour naked cocktail party. Everyone knows why they are there. There are no hidden agendas. I've met a lot of women who had no intention of going naked spend the entire week on the nude side. The reason is that it's a comfortable environment for women. That way she gets comfortable being naked in sexual situations. There is also a good chance you'll find playmates. It's also very likely she will want to return next year.