I agree with Jack. Flying into Orlando is usually cheaper than FLL or Miami. Port Canaveral has 3 and 4 day cruises. The 3-day cruises on Carnival Fantasy and RCI Sovereign of the Seas sail Thursday night through Sunday morning and the 4-day cruises sail Sunday night through Thursday morning.
They both sail to Nassau, The Bahamas, and one other stop. For Carnival Fantasy the other stop is Freeport (not much of a stop IMO) and for the Sovereign the other stop is Coco Cay (their private island).
I've noticed that beginning the first of the year the SOS will be shifting their schedule to Monday-Friday morning and Friday-Monday morning for 4 and 3 day cruises.