We did this cruise with Holland and America in early May sailing from Montreal to Boston and the second week sailed the return cruise from Boston to Bermuda, spending 3 whole days and nights moored on the main street in the town centre of Hamilton. Montreal & Quebec are lovely and we had a great time visiting the Anne of Green Gables farm from Charlotte Town but there was really nothing to see in Sydney (we have no idea why on earth the cruise lines bother to stop there but guess the mooring fees may be cheap as they want to attract tourists). Even the cruise tour guide said that there was nothing to do there. The next port was Halifax and that was interesting with an extensive range of shops and craft stalls in the port terminal building where we bought most of our gifts and souvenirs. Bar Harbour was beautiful and the tour to the Arcadia National Park on Ollie's Trolley was excellent and very informative. From there we sailed into Boston and would recommend the Boston Tea Party museum and the Hop on Hop off bus tours as a means of transport with a good commentary on the city. Bermuda was beautiful and the best and most cost effective way to see it and get around the whole island is to buy a 1, 2 or 3 day Rover bus ticket which is also valid for using the ferries. If you're leaving the ship in the morning in Boston and your flight is in the evening, we would also recommend booking the water taxi service that collected us at the wharf just outside the cruise terminal (an easy walk from the ship) and took us to their office in the centre of Boston where we were able to store our luggage for the day. We returned there to collect our luggage at the end of the day and they took us across the river to the quay opposite where we were able to get on the free bus transfer to the airport. In our opinion, May was too early in the year to visit as Spring had not arrived in Canada but the weather was warm and sunny in Montreal, Halifax, Bar Harbour and Boston.
