Yes, there are plenty of local buses that run until 8:30 pm at night. They cost 1100 pesos (or approx 60 cents US) per trip. The two buses the Decameron hotel guests use mostly are Centro which takes you from the Decameron San Luis to downtown area and Decameron Maryland at the beginning of the boardwalk or to get back to the Decameron San Luis, you hop on the bus that says San Luis. I used the bus system every day last November while staying at the Marazul. I went to Rocky Cay, San Luis, downtown to shop, etc. Taxis during the day are inexpensive; e.g. $5.00 to go from the Aquarium to San Luis. After 8:30, that price escalates to $15.00 (for instance).