Hubby and I went to Puerto Vallarta for our anniversary last year and I absolutely loved it. We only had a few days, but we took a tour of the city and a tequila distillery, swam with dolphins, and went to this island that is only accessible by sea for an evening. We had planned on snorkeling, but it just didn't happen. It didn't seem extremely touristy to me, but we went during off season.
A good website for more information, including a lot of fun activities, is
http://www.puertovallarta.net/index.html
Click on the tours and activities button on the left. There are endless things to do there, a wide variety of restaurants, and of course, lots of beaches. We didn't even make it to the beach because we were so busy. Hope this helped!!