We did the Trolly Tour. Unfortunately it was pouring down rain AND our Trolly got a flat tire. There is a rooftop over some of the trolly's. Ours had one but rain was still getting us pretty good. But they were pretty quick at getting another Trolly to us. If it had been a pretty day, I think it would have been a wonderful experience.
The last time that I did the Key West trolley, there were so many ships in port that, at every stop, there were small crowds of people waiting to get back on the trolley and the trolleys were full. You can buy a trolley ticket right where it starts, so you might want to wait until you get off the ship and see just how crowded it is. I still love this approach to site seeing, but I like being able to get on and off.