Have you ever heard of Mayakoba? A resort zone close to playa del carmen, the closest airport is Cancun (40 minutes drive to the hotel).
Mayakoba is 15 minutes drive from the famous village of Playa del carmen, you will find lots of options for a direct flight.
https://www.mayakoba.com
Hotels
I will recommend the Fairmont Mayakoba but there is a lot of others options.
The rooms are very clean and spacious, you can book a 2 queens bedroom for a family of four.
https://www.fairmont.com/mayakoba-riviera-maya/
Restaurants
They have an all inclusive formula with 5 restaurants on site at the Fairmont mayacoba.
In the village of playa del carmen you will have tons of restaurants choices from all around the world.
Beach
The beach is just beautiful, white sand ,clear water, beautiful landscape.
No big waves at all so it will be perfect for the kids to swim.
Strolling around the resort
Kids will love it because everything is accessible with golf cart.
Lots of fun for the entire family.
You can even do a free boat tour to discover the other hotels around.
Kids Club
Starting at 5 years old.
Kids club during the day, swimming, playing, drawing and movie night
For babies you will find everything on site, cribs, babysitting service
Enjoy your trip!