I love sea days! For me, the ship is the main draw, as penny mentioned.
I went on a 12-night RCCL with seven ports and although it was amazing, I was exhausted by the end!
Booked on Carnival Freedom, Feb. 2012 (Cozumel, Costa Rica, Panama)
NCL Gem, Sept. 2011
NCL Jewel, Feb. 2011
NCL Dawn, Sept. 2010
NCL Spirit, Feb. 2010
NCL Gem, March 2009
RCCL Explorer of the Seas, Feb. 2008
Carnival Miracle, May 2007
Carnival Conquest, April 2006
Caribbean Princess, Feb. 2005