Heck, I'm a nice guy, I'll give you my recommendations anyway.
My grandparents have been going to PV for over two decades (in fact, I think they live there most of the year now), so I went there quite a few times when I was a kid. I was last there in March '09.
Definitely go to Pipi's, great food and atmosphere....it's really busy, though, so you'll have to get there early:
http://www.pipis.com.mx/
If you are looking for a place to watch the tournament, a sportsbar called El Torito is probably best. Prices are reasonable and the food is good, unlike a lot of the places that cater solely to American tourists. I've never noticed it to be that crowded, so you can at least get the game on that you want. There's another great place called Casa Blakes (possibly even better than El Torito) for this, but there are a lot of Canadians generally here, and they want to watch hockey and curling, which during tournament time can be frustrating.
Other good restaurants include La Dolce Vita (Italian), Mama Rosa (Mexican), Agave Grill (Mexican), Los Arbolitos (though this is a pretty far cab ride into the older, poorer part of PV), Cafe des Artistes (expensive), and Daiquiri Dick's.
Night clubs? I don't know how old you are, but Carlos O'Briens and Senor Frogs are fun.
I'd spend a night to walk around the Malecon (a large beach front strip in the center of the city), it will be especially fun (and tough to get around) if you are there on March 21 which is Benito Juarez's birthday, a national holiday there.
Going out to Los Arcos (a large rock in the middle of the bay) to snorkel is also great (as is one of the many whale watching boat tours), but not sure how much money or time you have to spend to do that.