We used to belong to AAA, but I rarely used them for Disney trips. One year when we booked a room-only I bought park passes at AAA for a slight discount.
I also was able to get a AAA discount of 20% on the room only reservation which was nice because there were no other discounts available. I believe the percentage fluctuates, and is different for value, moderate and deluxe resorts. You can get the AAA discount even if you book through a TA or directly with Disney.
The also offer AAA packages, but I really don't think they are any cheaper than booking through Disney.
We get 10 % on park tickets. Discount on room only, I think was 10%. If you go to Universal, 10% on merchandise and food, ( alcohol too ) You also get discounts on theme park tickets. Oh, and of course the auto club benefits.
The best benefit of AAA is their roadside assistance, IMO. Although, anymore there are so many other sources of roadside assistance, often with your car, that paying for AAA may seem like a waste.
I've kept AAA for over 20 years because of how great the roadside assistance is. Once, we even had a car fail to jumpstart, and AAA diagnosed the battery, said it was shot cookies and radioed their battery truck to deliver a new battery. Didn't cost a lot more than buying one anywhere else either.
We regard AAA as breakdown insurance, particularly since DH is walking disabled and can't change a tire anymore.
Plus, our AAA TA is a real specialist when it comes to WDW. I think he loves the place about as much or more than we do.
"Too many people grow up. That's the real trouble with the world, too many people grow up."--Walt Disney
I ended up booking my POFQ room only reservation with the AAA rate this time, because there were lousy discounts offered this time. I got 20%, and the highest I saw from Disney 5% for GP or AP. (Also, you get a higher discount at Earl of Sandwich with AAA vs an AP!)
We like the free travel guides -- we order them anytime we start to plan a vacation -- and the 10% discount on hotels. Every hotel, pretty much, which is great since we stay in non-Disney hotels more often than Disney ones.