This is the only way I've been able to find it:
On AAA home page, click on the "travel" tab
On the next page, click on the "hotel" radio button
Fill in your dates, and in the city section, type "disneyworld"
Scroll down to the Optional: Hotel Chain section and go through those hotels until you see "Disney World Resorts" and select that one. Click on the submit button at the bottom of the page, and hopefully you'll get a laundry list of what is available on-site. You do have to be a little savvy about the rack rate vs. the AAA rate because they don't make it apparent when they show the rates.
Interestingly enough, last Sunday I just reserved a room for my January trip . CRO said the only value available at the AAA rate for my dates was ASMu, so I went ahead and booked it. Now I see that all of the values are available at the AAA rate except for Pop Century. Hmmmm.
Good luck and I hope this helps.