In 1956, the philanthropist Laurance Rockefeller donated 5,000 acres of St. John, more than two-thirds of the island, to form the Virgin Islands National Park. He had come to St. John on a sailing trip only four years prior. Enraptured by its beauty, he started buying up large swaths of land to ensure that it would never be developed. An additional 170 acres would be set aside to create...

Take the fairytale architecture and celebrity chefs of Las Vegas, add a water park straight out of the Disney playbook, plop it down on an island in the Caribbean, and voilà, you have Atlantis. To say this Bahamian outpost is a mega-resort is no exaggeration. Close to 3,000 rooms pepper the 171-acre complex, from the affordable and nondescript Beach Tower (a holdover from the days of...

Perched on 300-foot cliffs overlooking the convergence of the Atlantic and the Caribbean at Puerto Rico's eastern tip, this four-diamond resort is big—five "villages" that house a total of 983 rooms, including Las Casitas, a complex of 155 one- to three-bedroom villas that come with butler service. The resort also has 22 restaurants and lounges, a casino, tennis courts, golf, and its own...