If you're considering NOT going AI, then consider one of the Royal Resorts. There are many reasonably priced on-site restaurants at the Tri-Royals, two at the Royals Sands, and one at the Haciendas.
The Royal Haciendas is the newest and most upscale, and the jacuzzi on the terrace with ocean view is quite romantic
With free delivery from the Express take-out onsite, they'll never have to leave their villa. The beach is very nice, snorkling right there, and Play del Carmen accessible via resort shuttle or taxi.
Club Internacional is very quiet and peaceful, and close to the wide variety of Cancun restaurants and nightlife.
The Sands and Tris (Mayan, Caribbean, and Islander) offer lots of pool areas and restaurant options, and as with VCI, unlimited Cancun restaurants are just a cab ride away.
All offer the option of quiet dinners in your own villa with free delivery from the "express" onsite, and there's a nice selection of wine and other drinks at the minimarkets at all of them.
The Royals are always on the top rated TUG resorts.