We have stayed for two weeks at VDP and two at VDA, and have another two week stay coming up in Oct. at VDA. As the link provided above by rboesl indicates, you buy the AI in 3 day increments. Since there are so many nice restaurants in Cabo (and our favorite, Tobasco, which is just a short walk down the beach) we usually use one 3 day AI during the first week and the other during the second week. That gives us plenty of time to totally relax at the resorts during the AI days, and then go out and sample the local cuisine on the other days. And as the link also points out, the AI pass is good for restaurants at both VDP and VDA so there is plenty of variety.
Steve