I don't know if you're heading north or south from NYC, but for those heading north:
We used Dave's Taxi Tours in St. John and Open Top Tours in Halifax. Both were excellent! The areas we visited were all absolutely beautiful:
St. John:
Bay of Fundy trail - beautiful ocean vistas
St. Martins - walked in the sea caves (check the tide schedule!!) They have nice little place for lunch at the caves - try the seafood chowder - really, really good
Reversing falls - saw the river flowing one direction in the morning and then the opposite later in the day - seriously cool!
Twin covered bridge in St. Martins are charming and worth a photo stop
Quaco Lighthouse atop the Quaco ledges had a beautiful view
Halifax:
Cemetery with graves from the Titanic victims - definitely worth a stop
Prospect Bay - charming little fishing village with incredible views (and NO tourists!)
Peggy's Cove - it's lovely but crawling with tourists - we stopped there briefly, took our photos and hurried on our way
The place just down from Peggy's Cove that our guide called "Peggy's Cove without the lighthouse and people" - If you take a left on the highway from Peggy's Cove it was just a mile or so down the road. He turned left and drove up a gravel road to this beautiful vista. The rock formations looked just like the ones at Peggy's Cove. You could see the lighthouse WAY out in the distance. We were the only ones there. Not a soul in site, save a few sea birds. There was a picnic table so this would be a great place for a picnic lunch. I wish I could give better directions, but we had a guide and were just along for the ride!
Lunenberg and Mahone Bay - both charming little villages with historic homes, shops and restaurants and beautiful harbors. I wish we had more time at both of them. Either would make a great place to spend an afternoon if you had the time. If I had to choose between the two, I thought Mahone Bay was more scenic.
There are tons of little places to stop for beautiful ocean or lake (depending on the side of the road) views. We stopped as much as possible. Our guide was terrific, and knew all the little special spots. Both my husband and I are amateur photographers, so it was a perfect day for us.
Weather overall was much better than we expected. It was cold and drizzling at sail away, but by the time we got to St. John it really warmed up. Pirate night was windy and cold, but on the last sea day there were lots of people in the pools, it was so warm. Bring layers, that way you will be prepared either way! We thought the seas were especially calm, though I've read other reports on here from passengers who thought it was choppy.

I don't know, for us it was by far the smoothest seas we have ever sailed on. Maybe our previous cruises were just really bad by comparison!
Overall we loved this cruise. There were not a lot of kids on board and because of that the ship was not crowded at all even though it was almost completely sold out. I guess a lot of the rooms just had 2 in them. We would love to do this again some day. Sailing out of NYC was a treat for us as we didn't have to fly and we really enjoyed the ports.