When I have used my AAA card to secure a rate, they have always asked me for my card when I checked in. What hotel are you staying at? It's really hard to say. 3 out of 3 times I've been asked for it. If they ask you for it and you cannot provide it they may charge you the rack rate.
We are going in June and staying at POP for the first time. It will also be the first time that we are AP holders! If you have a AAA card and used it to get a rate then I highly recommend taking it with you. If you are worried about carrying extra cards into the park, then you could always just leave it in your safe. It's just better to be safe than sorry! Have a great time!
Our experience has been-if we have paid for the room in full in advance-they do not ask for the card. If there is an amount owing when you check in they have asked to see the card. Better safe than sorry-I'd have the card just in case.