LadyPhoenix,
Airfare booked via any cruise line comes with potential complications. In essence you do not have full control of your ticket particularly in the case of schedule changes or a mechanical or weather related issue for the airline. For domestic flights book your own air. For complicated foreign travel, which you did not ask about it's another story.
You do have to be onboard 90 minutes before the ship sails under the current Homeland Security policy.
MIA is about 20-30 minutes from the POM. MCO is over an hour from Port Canaveral. Both ships would probably embark between 4 and 5. If you fly into MIA you need to arrive by 11 to compensate for the mess that is MIA. If you are flying into Orlando you need to land by 10:30 at the latest.
Please also give consideration to enhanced security both at the airports and the ship.
For more information and advice log on to Cruise Critic. There is a Cruise Air forum with a Sticky about cruise air programs.
As a frequent cruiser, I no longer fly into any embarkation city the day of the cruise.