So I'm reading Peter Greenberg's Travel Detective. He is a big fan of shipping your luggage ahead of time. That way you don't have to lug it on the airplane. (Of course this makes TSA take a hard look at you now.) He mentioned FedEx and UPS and a few other carriers.
Since it is an older book I Googled "ship luggage" and got a huge number of hits. I took the first link (sponsored so maybe a little suspect) and poked around. For the DW & I to ship two 50 pound suitcases from our home to California, our next port, it would cost $230 each way. That is with shipping 5 business days in advance!
Maybe there are better deals out there. But unless I have to take something really large I think I'll stick with the airlines.
All I ask is a tall ship and a star to steer her by; John Masefield
Carnival: Glory 2004, Destiny 2008, Splendor 2009, Freedom 2011, Valor 2012, Dream 2013
Celebrity: Summit 2011
Princess: Ruby 2010, 2014, Caribbean 2013, Coral 2014, Regal 2014
Star Clippers: Royal Clipper 2015