We did the trolley. (not through Disney) There are quite a few pick up and drop off places with the trolley. It is open air. You can see and do quite a bit this way. I think there were 9 stops (I can't seem to find any of my stuff from Key West--navigators or brochures) We had been to Key West a few times before, but it had been about 7 years since we had been there.
When you take the trolley, you get some history and info about the Island. You can get off at any of the stops, tour, look around, etc. then get back on the next trolley that comes around. They come every 20 minutes or so. It gave us the opportunity to visit the Southernmost Point without having to walk *forever*!
Sue Ellen