My family is planning a trip to NS and NB this summer. We live in southcentral PA and paln on about a 15 day trip.
My wife loves puffins and would love to see a colony. And I read somewhere that there are ewxcursions to see icebergs, which would be totally "cool"(sorry) to see, too.
Are these excursions only offered in Newfoundland? If so, is it at all feasible to try to do these with a 15day vacation, counting driving times? Also, are there even icebergs that far south in the summer?

You may or may not see icebergs off of Nfld in the summer, depends on flow of the water, etc. And yes, it would only be Nfld you would see them. Nfld would be a trip on its own, not leaving time for any other province in your fifteen day timeframe.

To see puffins, the place you absolutely want to visit is Machias Seal Island, which is off the coast near the Maine-New Brunswick border. This is one of the very few known islands where puffins hang out in significant numbers and where people are allowed to visit.

The puffins are amazing. Although the puffins are everywhere, the best views are from the blinds -- the puffies come flying overhead, their little orange feet dangling as the come in for a not-especially-graceful landing. It's really an extraordinary sight.

The number of people and the places they can go on Machias Seal are extremely limited. Only 2 or 3 operators are allowed to bring people to the island, and no more than 60 or 80 people per day are allowed.

From the U.S., you can get to Machias Seal Is from either Jonesport or Cutler, maine. Of the two, Cutler is much closer to the island (andtherefore a shorter boat ride, which is a distinct advantage). I'm not sure about getting to the island from N.B.

Second the below recommendation of Machias Seal Island. In Canada, the trips leave from Grand Manan, New Brunswick, a very worthwhile destinaton on its own. Make reservations NOW, and dress warm if you go; the Bay of Fundy is very, very cold!

There are also boat trips to see puffins on Newfoundland.

You can see iceburgs in Newfoundland, but not NS or NB that I know of.

Make that "above recommendation" - it's late!