World's Best 2018 Awards Rank: #6 River Cruise Line
Best for: Luxury lovers searching for memorably fabulous Continental cuisine and top-notch service.
Sails: Rhine River, Main River, Moselle River, and Danube River
At a Glance: Crystal Cruises’ river ship cabins all have balconies and butlers … and they’re also all-ages, too. You may not think of them as family ships, but everyone six-months-old and up is welcome.