The beach at Barra Vieja, about an hour's drive south of Acapulco, is a lovely secluded beach where you can relax in a hammock, eat great inexpensive ceviche beachside and enjoy horseback riding and massages, but the swimming isn't great and security issues outside of Acapulco make it advisable to be back in town before nightfall or stay overnight.
Playa Blanca, Barra Vieja, Mexico