We were there for our first time in April of this year. One thing that we were skeptical about but did decide to do it was the Zipline. You have to do it! It was one of the coolest things I have done while on vacation. What a rush. We would do it again in a heartbeat. There is also a day cruise that goes from PV to a place I think called Los Arcos and you snorkel for about an hour and then you go either on a hike to a waterfall or you can ride horseback. When you get back to the boat they take you to lunch at a private beach, all the tour boats stop there, and then you head back home. We enjoyed that too. It does take up the whole day though.
There is a place to eat down by the end of the boardwalk and I can't remember the name of the place. I can tell you exactly how to get there and if you ask the locals about it they will tell you where to go. There is always a line there and the food is excellent. I don't remember the name being the one mentioned earlier but it is definately worth a stop. The boardwalk is also a very fun place to go in the evening. There are street vendors and performers all over the place. Don't rent a car. Cabs are very inexpensive and will take you wherever you need to go.
When you get there, exchange your money first thing. If you pay in american currency you will overpay for everything. It will be obvious when they ask you if you are paying in american and then the price changes. There are exchange banks all over the main drags.
I would also suggest getting a place that is not All-inclusive. You will pay a hefty fee for the all inclusive resorts and you will have a hard time spending that money if you went out to the nicest places and ordered nearly everything you wanted and then some. Staying at an All-inclusive place, we felt, would make us feel like we had to eat every meal there in order to get our money's worth. Some will also allow you to only do a few days of it so you may check into that too.
If you are into it, Senior' Frogs has a foam party that is really a ton of fun too. I think it is on Tuesday and Friday nights but it might even be more than that. It may sound kind of corny but when you get there and see it, what a hoot.
Shopping, that's a whole other subject.
Fishing- We chartered a boat where the captain was named "Pete" and he was a very honest and respectable guy. He was priced very well and worked hard for us. We didn't catch anything but neither did any other boats that went out that day that we saw or heard of. Like mentioned before, check with some of the other recommendations on the board and you should get satisfactory results.
Good luck and have fun whatever you do.