If you are a first time cruiser and don't know which particular line you'd like to sail, find a good TA that can tell you about each cruiseline.
Even though I do most of the online work myself, I continue to use my TA. One, because we have become friends; two because she tends to find special deals that I haven't heard about; and three because it may just be coincidence, but everytime I have sailed I have been upgraded (I usually book a guarantee) - once from a 6A oceanveiw to an 8B balcony.
CarnivalSensation February 2015
Carnival Dream November 2015
Carnival Fascination April 2014
Carnival Elation March 2011
Carnival Imagination Sept 2007
Carnival Sensation Dec 2006
RCI Sovereign of the Seas Sept 2006
Carnival Miracle Sept 2005
Carnival Glory Sept 2004
Carnival Fantasy Jan 2004