We had AP for a few years before last year when we changed to 21 day tix to get free dining.
There are no set amount on savings, we were lucky August 2 years ago, got AKL room for £71/night which should have been about £150/night then got free upgrade on arrival to Savanah view worth even more. Sometimes(peak times) the savings are tiny, other times great discounts.
No AP discount can compete with Free dining offer and upto 56% off at OKW/SSR, we have gone for that again this year.