I just called WDW main reservations number, gave my dates and room type and resort. They gave me the price with a AAA discount over the phone (and I had already found out the rack rate by looking on the WDW website for my dates) and confirmed my room, my resort, my dates were available under AAA discount (%off varies by resort, room type, dates). Availability is limited, so I was just like you, wanted to know what the % off was and if it was actually available before I enrolled in AAA. They would not hold the AAA discount room for me without my AAA number and expiration date, so had to hang up, figure out how to get my AAA membership (instantly showed me my temp card for AAA which had my number and expiration date after I enrolled in AAA online). Called right back to WDW and got the room reserved!
To find AAA discount code for membership in your state, google "AAA discount code <your state>". Hope that helps. Slick deals has lots of info on AAA discounts for different states. Notably, the thread that contained the link for the Texas discount was from 2010, but the code was still valid. So I guess AAA codes last a long time! Good luck!