I haven't stayed in San Diego but I noticed that the Hilton Resort there has scuba listed on the Hilton website. I suspect that may mean that there is a scuba operator's desk there or that the dive shop picks up at the hotel, but you really may be able to dive from the hotel. If you're making an award reservastion, the hotel is in the Premium or Level 6 category.

The Hilton Curacao has an on-site PADI dive center. The reviews that I've read about the hotel don't have much to recommend it though. OTOH, it's not too expensive.

In the Dominican Republic, the Marien Coral also has an on-site PADI dive center.

I'm currently trying to plan a trip for 7/1-7/6 which would let us scuba too. I'd recommend a couple things when trying to plan a scuba trip... 1) call the hotel directly and if possible, speak to the dive shop. Ask them pertinent questions like "If the hotel is full with 2,000 guests and the dive boat takes 20 people, how do I guarantee that I will get a spot on the boat?" or "If the seas are high on this side of the island, will a trip on the other side be subsituted?" or "Is there a dunk tank on-board for my camera?"

Also, check out
http://www.undercurrent.org

They have many reviews of diving locations and operators.