While I have never been to the big places like Playa, Cancun, and Cabo (as well as others) I have heard they have become incredibly Americanized to the point where it doesn't even feel like you are in Mexico. Even down where I am there are chain stores that are immensely popular. The other day I was in Costco looking for dogfood on a sunday with my pops and there must have been 500 people in there.