The three Pueblo Bonito resorts in Cabo are optional AI. The two on Medano Beach (PB Rose and PB Los Cabos next door) are within easy walking distance of town. The PB Sunset Beach has a free shuttle to the other two.
I booked an all inclusive optional in cancun and decided to try the buffet one night. I asked at the podium how to go about getting the buffet just for one night and the guy at the podium gave me a price much below the price if you paid inside. It was quite a bargain, they even supplied me with drinks-even though I only had two. I did this just a few times, as all you can eat buffets just are not appealing at any price. I rather go out to a restaurant, or cook in the room if they have a kitchen.
Did you get a bill for the buffet or was it more of a tip?
Very easy for the guy at the podium making good tips by allowing people to enter who do not have AI.