Had another thought as well. Since you have two that don’t dive - if they enjoy snorkeling I would take them to Akumal. It is a fantastic snorkel park with lots of marine life. The turtles love the area. It is not as commercial as Xel Ha. You can get there by cab or rent a car. It is only about 40 minutes south of Playa and well worth the trip. There is also the Akumal Dive Center - so you could dive and they could snorkel and lay on the beach. It is our second most favorite spot around Playa.