Henri--Does your budget allow you to rent a car in Bar Harbor Maine? Maybe you could split the cost with another couple from the ship. Because I think the one thing you should do in Bar Harbor is driving the Loop Road in Acadia National Park. It's a 20 mile road with various places to stop, take pictures, read about the history of the park, etc. Going up Cadillac Mt. is a must and is along the Loop Road. I would totally meet you there and take you to all the must sees, but it's 3 hours away and during the work week!
If you browse this site, you can get more info.
Click on Plan your Visit, then Things to Do and it will give you more info. I'm assuming you only have a few hours, so Loop Road would be the best choice.
You'll have to pay the park fee of $10, but that's per vehicle.