First off, our Tour Guide Tom Collins was hysterical and entertaining. Lots of great information and he quickly realized we were sports fans and added in sports trivia.
We got on at the Aquarium at 9:30AM... got off and went to the USS Constitution, walked to Bunker Hill, walked back and caught the Trolley. We did the entire loop on the Trolley, then got off at the beginning of the Freedom Trail, walked the Freedom Trail, we were done by 4pm and then caught the Trolley again at Boston Common.
There is another Boston Trolley tour company and they share the same stops. The other Trolley folks had to wait for multiple Trolleys because the Trolleys were full. Using this company there was always room and the Trolleys run every 10-15 minutes.