In Cozumel we loved Mr. Sancho's...we grabbed a cab, went there right away in the morning. The beach is beautiful, there are lockers, showers, very, very clean bathrooms. There is a large restaurant, you can eat inside or out in the sand. The food is delicious. There is also a swing bar (the seats are swings).
That doesn't even count all the things they offer to do there. Water trampoline for the kids, horseback riding, atv rentals...there are some nice little shops. You can check it out at mrsanchos.com.