I love to travel. I also love cruises. I've been to an all inclusive resort. I took my wife to an all inclusive resort that was adults only.
Based on what you've said, I'd either go on a cruise or to an adults only resort. The adults only resort we went to was adults only, meaning "no kids" under 18. It was a nice resort, but not XXX. We had a wonderful time. It was on the east coast of Mexico, Riveria Maya. It had six restaurants, and the worst was very, very good. It was all inclusive and everything was included, but the fancy liquor. (We don't drink so I can't explain their liquor policy.)
Cruises are also great. The cruise lines now have adult only pools, spas, and jacuzzi. If you don't like to walk, get a cabin close to the rear (aft) of the ship because of where the restaurants are, unless you are staying on the 5th floor or lower, then opt for the center of the ship. Unless you are super sensitive, I wouldn't worry about sea sickness. Ships are so stable now that they have bowling alleys and miniture golf courses on board.
If you like to save money, then check out the travel web sites. They have some real good deals right now. I used cheapcaribbean.com, but travelzoo.com and shermanstravel.com also have real good deals. Many of their travel deals include airfare.
Be sure and get a passport. They are now required for any travel beyond our borders. Apply NOW if you don't already have passports.
Congratulations on your 15th anniversary. Good luck to you and yours.