We opted for the hop-on/hop-off trolley, only, to fill the end of our day in Boston. The trolley provided an overview of Boston's top sites - a plus if it's your first time in Boston as it was for 2 in our group. We rode the entire route and then again to get off where we decided we wanted to explore more. Get an earlier start - we were on the last trolleys so once we got off, we walked back to our car since the trolleys were no longer running.
Our driver was a bit crass with jokes over the heads of the younger crowd. You either like it, don't like it, or ignore it. We didn't mind.