Are you looking for any particular type of food? When I was down for a sight visit, I checked out a couple potential locations for a rehearsal dinner. One was La Casa de Las Margaritas. La Casa de las Margaritas, Cancun - Discovery Mexico
It was a very cute place and the margaritas were fantastic.
We also looked at a place La Dolce Vita (Italian Seafood). La Dolce Vita Restaurant Cancun Mexico Serves Italian Seafood in the Cancun Hotel Zone for Dinner, Lunch, Parties, Weddings and Catering
I have some information on both. If you are interested send me an email and I will forward what I have (including pictures).