Royal Caribbean's newest ship, Symphony of the Seas, is the world's largest, boasting more than 2,800 rooms. Innovative high-tech entertainment abounds, including Flight: Dare to Dream, a show with 3D flying technology; Battle for Planet Z, a laser tag battle with glow-in-the-dark action; and robotic bartenders at the Bionic Bar. For an unforgettable family vacation, book the 1,346-square-foot Ultimate Family Suite. This two-level suite can accommodate eight guests and features a floor-to-ceiling LEGO wall, an in-suite slide, a private cinema and a personal Royal Genie to make every cruising wish come true.