SJU would work for this. Try the Caribe Hilton or Condado Hilton. Airport to hotel is about $20, and you can either walk the Condado area or take a quick cab to Old San Juan for the day.

The Condado is cheaper for food/drinks, but is part of a small area of the public beach. The Caribe has a private beach and pool area that is great, but they're awful proud of their prices there. Depends on if you're a big drinking family or not, and how much you want to eat on/off property.

Edit: As an example, a Medalla in the hotel gift shop is $3/can. At the poolside bar, it is $7. Same beer, same size, just poured in a cup. As you may see in a thread from a few days ago, I confirmed that they do not allow outside drinks there, despite previous trips never having a problem. Last year, the rules varied daily, and I'd had enough. Since I drink when on vacation, I'll be going somewhere else next time. The Caribe is a great hotel though - especially for what you are wanting - despite what some threads here say about it.