The Palace Resorts in Mexico are outstanding. We stayed at the Moon Palace this past September. The beach wasn't the greatest but everything else was spectacular. Amazing food (several first class restaurants), the best pool I've ever seen at a resort (and I've stayed at a lot of them over the years), excellent staff, and plenty to do in the evening for entertainment. When you stay in one of their resorts you get to go visit any of the others during the day and use their facilities. Xpu Ha Palace has an outstanding lagoon for snorkeling and a nice nature preserve as well. Aventura Spa Palace has a spa that your wife will love. My fiancee went to the spa while I went cave diving.
The Moon Palace is just outside of Cancun while Aventura Spa and Xpu Ha are about an hour's drive south in the Mayan Riviera. About mid way between the two is a ferry that will take you over to Cozumel for a few $.
http://www.palaceresorts.com/