We bought tickets only through AAA last Oct. and saved quite a bit of money and were given our AAA diamond parking pass. Just keep it in your car/rental car and show the attendant when you arrive at each park. There is a blue line to follow for regular customers and a red line for AAA diamond parking and handicap parking.
The AAA parking is right next to the handicap parking and is RIGHT by the entrance to each park. It was a nice perk as we didn't have to wait for trams at the end of the night and it was an easy walk back to the car for sodas (we brought a cooler and used ice from our hotel), change of clothes, etc.
You'll have to look at your pass from AAA though, there are some black-out dates for certain parks. For example, we were there during the Halloween party at MK and MK was blacked out for those dates. However, we went to MK 3 times that trip and twice were still allowed to use it. It never hurts to ask.
