We are going to be cruising from Chile, by Antarctica, and ending in Buenos Aires. Last year, we did a Panama Canal cruise and for the first time I didn't book any excursions ahead of time. We found plenty to do in each port, either hiring taxis, walking around cities, or finding tours at the dock. We enjoyed the spontaneity of it. For our upcoming South American cruise, I have booked penguin tours at Volunteer Point in the Falklands and Punta Tumbo because I wanted to make sure to see them. Are there any other "must see or do" trips that we should schedule ahead of time? Will we be able to find tours at the docks or should I keep looking for them now?