Car rental question

[supamaki]

Are the rates for car rentals at WDW more than the airport, or the same. IS ther selection better or worse? I'm going to WDW for my honeymoon, and want to rent a car, but would also lioke to surprise the new wife with a Limo to our hotel. Should I scratch the limo and rent a car at the airport? Also what's the best way to get a discount on rentals? I'm a member of AAA, DC, and some others, but all the codes, and stuff is really painful to keep plugging in. If anyone can help I'd really appreciate it. I'll be there from Aug 19th-Sept 3rd, and want either an SUV, or a convertible.

Thanks a million