disneymom1,
Disney air: Advantages, if there is a problem, like a huricane (if you can imagine that) weather realted problems on either end, etc. Disney is responsible for making changes and doing whatever they can to get you to the ship. In some cases if people are coming in late as a result of air travel problems, they even hold the ship for a while. Since you typically fly in the same day as your departure, you also get to tag you bags with the
DCL luggage tags, and once checked at your departing airport, you don't have to touch them again until they arrive at your stateroom. Also, if as has happend this hurricane season, the ship is not able to dock as scheduled, DCL takes care of chaning your air arrangements. All of this adds a little piece of mind to the trip, knowing that contigencies are taken care of by someone else.
Disadvantages: Disney air is generally more expensive, you get their speical group rate and no other savings. You have to fly when and how (such as connections) they tell you. So you have very little control over when you get to Florida and the port.
We have done this both ways. On our first trip, a land and sea combo, we did everything through Disney. Since it was a totally new experience to us, we wanted as much taken care of as possible. For our last two and this cruise we've booked air fare ourselves. As a family of 5 we needed to get a better deal and we wanted more control over arrival. This time were flying in the day before.
However, also on this trip we are taking two of DW's relatives, for a trip we gave them for Christmas. Since it was originally scheudled for two of her elderly aunts, we booked their reservation with Disney air. Since we were going to be traveling together we wanted to make sure that they didn't have to worry about anything and all would be taken care of by DCL.
So it comes down to personal choice and which options make you most comfortable. Good luck with the planning.