You should know that discounts are NOT stackables. So you can either use a public code, a PIN, or AAA, be it for a room-only rez, or a package.
As an example, room-only gives you a 15-30% off depending on season and type of property.
Packages are also discounted but the savings are based only on the room part of it. I.e. if you price a room-only with AAA, and tack on tix, you'll spend about the same on a package.
Now, local AAA offices sell tickets with a discount, but some vary in lenght and some require the water option.
Finally, the only other 'perk' you get is a parking pass to the AAA diamond lot on MK.