The beach in the Marina is sandy. We stayed at the Mayan Palace, next door to the Club Regina, several times, and have enjoyed walking on the beach there.
As for swimming, there isn't a single location in the entire PV area where I would think of swimming. But the beach in the Marina area (extending to the north of the entrance to the marina) are swimmable and I have often seen people in the water near the hotels and resorts along the Marina waterfront.
I don't know what the beach situation is like for the resorts in the Hotel Zone (i.e., near Bouganvillias and Vallarta Torres, for example).
I think there are few timeshares just south of downtown, in the Romantic Zone. Those would be close to Playa de los Muertos, which receives a lot of recreational use.
There are also timeshare resorts further down the coast, starting in Conchas Chinas and extending toward Mismaloya. The only beach in that area that we have visited is Mismaloya, which is nice and is used recreationally. I think that the other beaches in that area are probably pretty skinny, and might often be rocky instead of sandy.