In Puerto Vallarta, the Malecon is a beach promenade right in the downtown. It's not the best beach for snorkeling or swimming, but they have parasailing and jet skiing from this beach, and lots of activity. It's right in the middle of the pretty old-town area of Puerto Vallarta too -- with, cobblestones, shops and restaurants. It's easy to get to by shuttle or taxi from the cruise pier.
Yelapa is a farther away beach, only accessible by water taxi. It's got an "island" type feel, with palapa restaurant, palm trees etc. There are watersports available from the beach, but it's got a quieter, away-from-it-all feel.
There's also a jungle canopy tour in PV. We didn't take it, but might be fun for teens.
We did Yelapa in May of last year and loved it love it loved it. Good food, vendors come to your table and good beach and water sports. Not commercial AT ALL! Would recommend checking it out! Bon Voyage!
My reply has nothing to do with your question, but if you are interested, I do shore excursions in Mazatlan. I have an air conditioned van for up to 10 pax and also a nice open air trolley for 30. My tours are flexible and I take you to where YOU want to go. I give you the choices and you pick where to stop. Great prices too! Contact me for more information at: