I have a room only ressie (2 rooms) at the POP this July and I only got 8.5% discount. I was kind of surprised, I assumed it would be the 15%. I booked directly through disney. I checked the AAA website and was quoted the same price.
We're saving a ton at the CR this Easter, so AAA more than paid for itself and we're saving approx $100 this summer for the 2 rooms for 5 nights.