Well, I'm new to the whole "wedding planning thing", but I've been to Cancun about 24 times, so I feel I can answer lol!
You should try either Riu Palace Las Americas or Riu Cancun because, in all honesty, those are the only AI's I can think of that are on the "calm side" of the water: Cancun is shaped like a "7" and those resorts on the top of the 7 have calm waters, because the waves are blocked from Isla Mujeres a little across the way. So, I would start your search there