If you decide on Carnival think about going out of Tampa. There is a 5 day on October 22 and a 7 day on the 23rd.
If you do Carnival I have a very good person I use at Carnival to book with. She is knowledgeable and will get you the best deal and cabin.
TPA is an easy airport to fly in and out of. The cruise port is a about 15 min from the airport. There are also lots of hotels with transfers from the airport and to the cruise terminal.