Check out the Grand Hyatt in Playa del Carmen. It's basically a mini-resort, but smack in the middle of PdC with its awesome restaurant scene. I'd do breakfast everyday at the hotel (just to make life easy), and venture off for lunch and dinner. They have a kids club where you pay a la carte for care, plus a Teens Arcade.
You can do that for way less than $1-2K for per night. Definitely sounds like a good place for kids a bit older (like your's). My kids are too young, so probably would better benefit from a AI.
https://www.hyatt.com/en-US/hotel/mexico/grand-hyatt-playa-del-carmen-resort/cunpc