Thankfully, much of what I love about St. Barth’s doesn’t change—Saline beach, the two-hour lunch custom, its sophisticated yet bohemian spirit—but on my recent trip, I found some noticeable upgrades and additions. Le Guanahani and Le Toiny have had major renovations. (In fact, Le Toiny’s new owners, the visionaries behind Isle de France, have created a beach club that is a must-stop for lovers of a long, lazy lunch.) La Guérite is the new hot spot in Gustavia for dinner, and shops like Baya and...