Most flights to Haiti leave from Aeropuerto Herrera. Carriers include Caribair and Air Guadeloupe, plus I believe one other -- can't remember the name. Terrabus is extremely nice, though, and will allow you to see the Haitian and DOminican countryside. I would recommend Terrabus. I know that there are two and three day bus tours to Haiti from the North Coast, notably from Puerto Plata, Sosua and Cabarete, but I have never heard of them along the south coast. One reason might be that Cap Haitian on the Haitian north coast is more interesting and beautiful than Port-au-Prince. Along the south coast the best spot is Jacmel, south of Port-au-Prince, but there are no flights here -- you'll have to take a long tap tap ride from the Haitian capital.