3Mouseketeers - Well, here is what we did in September - it worked well enough that we're doing it again next week & it was much cheaper for us than using a towncar service from the airport.
Using National Car Rental - you can sign up for the Quickrent feature when booking on-line. The vehicles are all located directly across from the baggage claim area at MCO - you can just walk directly there, it is right on-site. If you use Quickrent you can just pick out a vehicle in the section for the type of car you reserved (example: we reserved compact, so we go & pick out a cavalier in the compact section - it is clearly marked for you.) Then you just drive to the booth at the exit & hand them your ressie, drivers' license & the credit card you booked with. Now you're on your way to Disney! It is really fast & simple, no counters to deal with or anything.
Next, we drive straight to our Disney Resort & check-in. After unloading the luggage & resting for a bit, we drive over to the Dolphin (there is a gas station right near there) & return the car to the National Car center there. From there we usually just hop a bus to a park, but you could also hop a bus to Downtown Disney for some shopping/eating.
Then, on our departure day, we head to a park for half the day, then hop a bus to the Dolphin. Go to the National Car counter & p/u the keys to our vehicle - the valet will then bring the car around for you. We go back to our resort, load up the luggage & drive to the airport. Drop-off at the airport was pretty easy, too. Just follow the signs for National & pull-in, they will do a quick look-over of the car & then you're on your way.
For our trip next week, one way is $25, the other way is $30. Way cheaper than the towncar, and more convenient in my opinion - we can do everything on our own schedule.
Hope this helps you out & doesn't confuse you further!