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.

ankopsu Article on Boston

I went on two tours alone...I made life-long friends along the way! That's the nature of Contiki.

efti Article on Travelling alone

Winter is an excellent time to go to Europe. There are next to no lines for the museums, you can experience the cities like the locals do and everything is cheaper! Plus, Christmas and New Year's Eve in Europe are very special.

Mike Contiki Article on Tours - Winter Europe