As the first new luxury ships to be designed in a decade -- debuting in 2009, 2010 and 2011, respectively -- Seabourn Odyssey, Sojourn and Quest boosted the luxury ship spa concept to new levels. The sprawling two-deck spa facility is surprisingly large for a small ship and offers everything from a Kinesis wall to Finnish sauna. Also intriguing are Spa Villas, each featuring an oversized bathtub, balcony, living area and daybed. Each 2.5-hour session in the private villas also includes a spa treatment.