We got married in the Riviera Maya, Mexico in Oct 2006. We had previously stayed a few times at the Iberostar Paraiso Del Mar and had some wonderful stays there and decided to get married at the neighbouring IB* Paraiso Maya. We booked both the holiday and wedding package through Thomas Cook and from start to finish we had a fantastic time. The downside to a Mexican wedding was the mountain of paperwork before travelling which all needs translating and authorising by the Foreign Office, though this is common with many overseas wedding destinations, and the Mexican requirement for a blood test in resort prior to the wedding.
The Iberostar Paraiso hotels are on the coast halfway between Cancun and Playa del Carmen. Four of the hotels, Del Mar, Beach, Lindo and Maya are family hotels with the Beach and Del Mar having the least facilities, a la carte restaurants etc. (and the least expensive!). We loved our stays at the Del Mar and they would be ideal for holidaying with a young child. The top hotel on the resort is the adults only Paraiso Grand, an outstanding hotel which gets rave reviews. We stayed at the Grand last October and it rates as the best hotel we have encountered anywhere. A plus to the Iberostar Paraiso hotels resort as a wedding destination is that family and guests (assuming there are any!) can opt to stay at a hotel which is suitable in both cost terms and also whether they would prefer an adult-only environment. You can dine/drink at any of the hotels in the category you have booked or lower.
We looked at staying at the Azul Sensatori next year and it looks excellent for families. We were ready to book it for March but then changed our minds and booked the Valentin Imperial Maya, however this wouldn't be suitable as it's adults-only.
Good luck with whatever you decide.