One of my best friends from college got married at the Iberostar north of Playa del Carmen in Feb 2004 (that's what FINALLY got me into diving). I think they have a resort in Cozumel, but you might consider these resorts as well. Then you could escape to Cozumel to another resort for your honeymoon. (My friends went to a couples only resort after the wedding)
Here's what I remember she said about why they picked Iberostar and other topics.
The marriage was legal rather than a symbolic one. I think it was a local judge/justice of the peace who performed the ceremony. They needed 3/4 witnesses who had to be in the country for at least 3-4 days. I was able to serve as a witness but the resort could have provided them.
My friend was very happy with the wedding co-ordinator that she worked with at the time. I know she checked out various places. There were other places where she wasn't happy with the response from the wedding team.
One of the pluses was that in this resort they would only allow one wedding per day rather than 2-3 as other resorts did.
The salon/spa on the property took care of my friend's hair/make-up, etc. She was happy and didn't have any test runs. I am sure you could have brought in others if you had wished.
We had the entire restaurant both on the night before and the wedding dinner (in 2 different ones).
There was a gazebo in the gardens or the beach as the choices for the ceremony. We had a wedding on the beach. Her ceremony was around 17:00. I think you could pick the time but they advised based on the sun/light/color of the water.
The resort was suitable for the range of the guests that attended (singles, married with kids, all age ranges). I think everyone had a great time. I would probably honeymoon somewhere else if you want something more romantic or private (big family focus).
If you want more details or want to contact my friend, PM me and i'll see if my friend would be willing to be in touch with you (she has twins now so a bit hectic in her house).