If you're still a little timid, but craving some excitement, II's and III's would be right up your alley. Try III's and IV's. Class VI may be for you. Rafts are the big rubber boats that can accommodate roughly 6 to 7 passengers comfortably. Some of the larger ones carry 14 to 20 passengers.
Canoes are great for paddling around on lakes and running the more placid-type rivers.
Class IV and above are not really recommended unless you're an experienced pro. Those cute, colorful, lithe little enclosed boats that appear to be part of the paddler's lower body. Some are made of fiberglass, and some are inflatable. I'd definitely recommend lessons if you're seriously considering this kind of activity. It is imperative to learn proper techniques in order to handle yourself and the kayak.