We have cruised Alaska a number of times with NCL. Our last time on the Pearl. We did not take a balcony but an Ocean View, picture window. It worked out fine, we also bought the spa package, that was really nice as you could sit in the sauna in the fwd part of the ship and watch the glaciers from there.
We tend not to take any excursions now, we just walk around town and take in the sights and have a brew in a local bar.