Last Updated: 24th Feb 2014
The trolley tour of Boston, offered as an optional, is the best way to see the entire city. Take it at your own pace, but I would suggest stopping off at the USS Constitution and Fenway.
I went on two tours alone...I made life-long friends along the way! That's the nature of Contiki.
My advice would be to do as many excursions as you can. They are a great way to get to know your group, and they are always good fun.