Many people fly into FLL because it is less expensive. Check here for transfers http://www.floridalimo.com/
Are you coming the day before and staying at a hotel? or flying in the morning of your cruise? If it's the morning of, I would recommend flying into Miami. If it's the day before, relax and enjoy Ft. Lauderdale and ride the water taxis. The above company will pick you up at your hotel and return you to the airport when you return. Enjoy.