For the tuna, very large dorado and the giant tarpon in the Keys, choose a 12-weight outfit. These fish require a powerful rod that will ''lift'' fish from below the boat. A 10-weight would be ideal for many species in Baja, including all but billfish, very large dolphin and big roosterfish. It would be excellent when throwing big flies in the Cape Cod area and for all but the very large sharks and tarpon in Florida. My third choice would be an 8-weight rod. In fact, with these three rods you can go virtually anywhere in salt water and be well-armed.