Things to do in Punta Cana?

Does anyone have any advise on what there is to do in the way of excursions in Punta Cana? It appears to me like alot of days trips are in the North Coast. What is the best way to get from Punta Cana to SD. to see the city for the day?

Most hotels have a rep on site who can suggest several day trips in Punta Cana. Last year when we were there, there were about 8 or so trips we could take. We just took one.... a tour of S.D. The whole trip was done through a tour company and lasted a whole day. But with a tour company remember you are set to their schedule. Some ladies on our tour wanted to stop in some local shops as we walked by but they weren't able to because of time.