I think you'll enjoy Royal Caribbean. I loved the Explorer of the Seas.
Sometimes it's good to mix it up a little. Do a little RCI and maybe another cruise line. You can always come back to Carnival if you want...it's all up to you and how much you enjoy the others.
The Grass can be Greener or just as Green...you'll never know unless you jump the fence every once in a while.
Whichever one you decide to go with, I wish you the best of times!
Renee - The better half of RobRen :-)
Carnival - Spirit: Alaska (August 8, 2007)
Carnival - Miracle: Exotic Western Caribbean (April 9, 2006)
Royal Caribbean - Explorer of the Seas: Eastern Caribbean (January 2005)