Boston is a great historic port, and many of its features are close to the harbor. Union Oyster House is a great place to have lunch or dinner for people who have never been to the city before. The Duck Tour is also a fun diversion.
We spent several days in Old Montreal at the end of our cruise. Must sees include the Notre Dame Cathedral, the arts and crafts market and the home of the first French governor. Take a carriage ride with a narration to get oriented to the city. The harbor cruise "Bateau Mouche" is not worth the money - you see more with a city tour of the Old Town.
Bateau Moches Rating:
The harbor cruise doubles back on itself, so you're really paying for a duplication of the first part of the cruise. In addition, there are few really interesting sights on the water. You see more and get your money's worth from a good horse drawn carriage tour of the Old Town