The trolley is an option, but if you are just looking for transportation to see Key West and to get on and off, I would recommend the Bone Island shuttle (run by the same people as the trolley). It is an air conditioned mini-bus that has two different routes available. It is only $7.00 per person for the day, or about 1/3 the cost of the trolley or train. They also sell discounted admissions to get into the Hemingway House. Also, the shuttle is the only air conditoned vehicle of the three major options.