You might want to consider basing your trip out of Playa del Carmen. You can dive in the ocean and in the cenotes as well if that is of interest to you. Cenotes are generally considered to be a highlight of any dive trip to the Yucatan Peninsula and they are an amazing experience!
While you're diving, your family can enjoy the beach, visit 5th Avenue to people watch/shop, visit one of the children's parks in the center, etc. Playa is a very walkable city and easy to explore. On days you are not diving, it's easy to visit other parts of Quintana Roo, for example Tulum, Akumal and take in other activities with your wife and daughter.
Be aware that Playa is busier than Cozumel, but you can still feel as if you are getting away from it all - depending on the hotel you choose. There's a wide range to choose from - on beach or off, small & intimate to the large all inclusives. Wherever you go, have a great holiday!