We cruise Maasdam's Canada/New England itinerary every summer back-to-back and have very much enjoyed the Acadia National Park/Cadillac Mountain Tour with lobster lunch. Unfortunately, the better the weather, the huge difference the enjoyment and you can't know the weather in advance.
We have had sparkling bright, sunny day and looking down to the harbor from the heights of Cadillac Mountain was fabulous. This tour is offered in Bar Harbor.
We are sailing on the Maasdam round trip out of Boston in August.
I visited the Maritimes on the Star Princess in Oct 2006, and particularly enjoyed the "Reversing Tides" excursion in St John, New Brunswick. It is a ride on a small boat during the time when the tide is swirling in the Bay of Fundy and it was a lot of fun - prepare to get wet, although protective outerware is provided. Unfortunately, we will not be able to experience it this time, as the tide conditions will not be right.
Make sure to walk through the market in St John - well worth the time to see the local wares (the fruit wines were delicious!)
The view from Cadillac Mountain is spectacular - we had a crystal clear fall day at the summit.
"I must go down to the sea again"
Since a clear day would be best for the trip up Cadillac Mountain, you could wait, see what the weather is, and then do the trolley ride on your own. Easy to do. As I recall, tickets for the trolley are available right in the building where the tender arrives. It was a nice narrated ride with gorgeous views of Frenchman Bay. Lobster is readily available in almost any restaurant in Bar Harbor.