So we stayed at the Iberostar Maya on the Maya Riveria a few weeks ago. Only 30 min from the Cancun airport. All inclusive. Awesome beach. Food was good, all you can eat. Staff was outstanding. Quite a few families staying there with small kids.

Day 1: Beach Day

Day 2: Ruins @ Tulum, and then Coba. Lunch. Then swimming in a cenote. Booked online with Mayans Explorer. If your group is 5 people or more you get your own vehicle, driver, and guide. This gives you more flexibility in activities and timeframes, which was really slick for us.

Ask to have Luis Luna as your guide. He has a broad depth of knowledge and is user friendly. He doesn't try to steer you to his buddies store, but he will participate in the bartering process to get you the best deal. Things like pretending we are getting behind the rest of a tour group and telling us we have to go now (prices immediately dropped to whatever we had offered).

Tulum gets super busy super fast. They will have you there as it opens.

Coba is a very cool site. Huge and mostly uncovered, you ride bikes through the jungle to get from ruin to ruin.

Lunch was at a local buffet. Food was good. Luis/tour group paid for all meals, tickets, and entrance fees.

They then took us to a local cenote, all underground. It had two diving platforms and little fish that would nibble at you feet if you held still.

Day 3: Beach day. Legs super sore from climbing the pyramid at Coba.

Day 4: Ruins Day, a long day.
We start out by visiting the town of Valladolid. We go through the market, town center, and an old church.

Then on to the ruins at Chichen Itza. Tons of vendors here. Best place to barter imo. Luis can help you with it.

Lunch was at a buffet next to a big cenote. Kids swim and dive in the cenote.

Then we visit Ek Balam. This is a newer site. They let you climb all over these ruins. A burial chamber was found behind a false wall on one of the buildings so there is original mayan artwork/stucco to see here. This is a smaller site but well worth the stop. There is another beautiful cenote you can play in here but we were out of time. This site is not heavily visited but well worth the stop.

Day 5: Beach Day

Day 6: XPlor, and am stuck at the resort with food poisoning from a hamburger I ate on the beach. My wife and kids loved visiting the ruins, and they will tell you xplor was their favorite excursion.

Day 7: Sadly, we have to go home.

A few thoughts.
Bring a ton of $1 bills for tipping, and some fives and tens. Minimum wage there is $5/day so you have an opportunity to help some people out.

Though the resort had tons of pools and some kid friendly activities, we didn't use them. The kids preferred to play at the beach (ages 17, 14, and 12).

We booked our trip through Velocity Tours and Travel in Utah. They book the tours for all the HEFY groups and easily beat the prices we found online. Dave was the name of the guy we used.

Good luck.