From what I remember, the discount wasn't huge ($5-10 a night) but the extra perks were great. I think the Harry Potter extra hour was more due to our hotel being a partner rather than the
AAA but we got it so that's all that mattered. With AAA, we got priority seating to 4 or 5 shows in both parks which was nice to get first pick of seats and get out of the sun earlier than the rest. We also got City Walk party passes so we didn't have to pay cover to any of the bars/clubs - I definitely recommend City Walk at night, it was great! We also got free souvenir cups, first fill free. We didn't really want to carry them around the park and they're nothing special but we got them on the way out one day which was great for free.
I bought the Unofficial Guide Beyond Disney and followed their suggestions exactly... it was perfect! It seemed like we just beat the crowds everywhere. The book is basically everything in Orlando that's not Disney - so Universal, Sea World, non-Disney waterparks, local restaurants etc. Highly recommended.