ATMs are the best places to obtain pesos; they're convenient and safe, and they offer the best exchange rates. You'll also find many casas de cambio (currency exchange offices) around the zócalo and along the Costera. Their hours are generally Monday-Saturday 9-5. Most banks are open weekdays 9-3 and Saturday 9-1.
Banamex (Av. Costera Miguel Alemán 38-A, Costera. 744/484-3381). Bancomer (Av. Costera Miguel Alemán at Calle Laurel, Fracc. Club Deportivo, Costera. 744/484-8055). Bital (Calle Jesus Carranza 7, Old Acapulco. 744/483-6113).
Casa de Cambio Austral (Av. Costera Vieja 3, Old Acapulco. 744/484-6528). Casa de Cambio Servicio Auxiliares Monetarios (Av. Costera Miguel Alemán 88, Old Acapulco. 744/481-0218). Dollar Money Exchange (Av. Costera Miguel Alemán 151, Costera. 744/486-9688).