After further research, I have been recommend to Isla Mujeres. A ferry ride off of Cancun. We've not been there yet, but are are looking at the Avalon Reef Club. There is a snorkel spot on the resort called "Kings Bath". Check out Trip Advisor for more info. If you find out any more info, I would be interested in it.

Decent to quite good snorkeing in the Riviera Maya:

Akumal Beach Resort - good snorkeling right off the beach (which is quite nice) and in Akumal Playa (little town just next door). Also it's not far from Yal Ku (good snorkeling lagoon). However it is a 3* resort and does not have all the facilities the big AIs do. We stayed there and liked it just fine.

Barcelo
Beautiful beach and decent snorkeling. I have not stayed there but I checked out the beach and people said the snorkeling was good.

Grand Palladium Riviera Maya
Beautiful Beach and good snorkeling. We have stayed there twice. Pretty good snorkeling (lots of fish) directly in front of the White Sands section(rocky entry there) and a nice beach area in front of the Kantenah section (nice sandy entry there and some fish). I don't consider the food "gourmet" but it was plentiful, varied and generally good.

There are kids at all 3 of these resorts. At the Grand Palladium there is a very quiet adults only pool. I never found the kids to be obtrusive at either the Palladium or Akumal Beach.