Had one the worse experiences with the Hop-on Hop-off trolley in San Diego. The trolley stays on the same path the entire time, every location it goes to in on the same loop, so if you are getting on at the bayfront Hilton location, it will take you straight to Coronado, and then loop all the way back around to the first stop. Also by the time the trolley got to me, it was beyond full, waited for 5 trolleys before I said screw it and just started walking, took me an hour and a half to get my money back, and even then they didn't want to refund, terrible experience.