As mentioned in the review, the hop-on, hop-off pink bus seems like a nice alternative but the wait at the cruise terminal is not. The tour guides on the bus seem to be knowledgeable.
Peggy's Cove was a little of a disappointment. There is not a lot to see or do there and it is about a 1-hour bus ride to get there and back with about a 1-hour stay at the location. There is a light house there, but you won't get to go in it.
Bar Harbor is very scenic with narrow streets packed full of small local shops. There is also a place there (I don't remember the name) right on the harbor that serves a wonderful lobster bake with a beautiful view of the bay with the fishermen all dropping their lobster traps. We really enjoyed this. All of the eateries seem to have fresh blueberry pie. I didn't think I'd like it so much, but it was delicious and I highly recommend you try it if you haven't before.
Newport is also a beautiful place. The tours were all sold out before we reserved one, so we walked everywhere when we got to shore. We enjoyed seeing the catholic church where JFK married Jackie in 1953 and also toured one of the mansions that was not too far from the cruise terminal.