We were on the Golden Princess, roundtrip from Seattle, in 2010. The Golden Princess has proven to be one of our favorite ships. We were on the starboard side, toward the front of the ship, and were happy with the location. You won't be in the open ocean so rough seas won't be an issue.
There was a naturalist on board named Michael Modzelewski. He gave several fantastic presentations. If he is still on the ship, and you have an opportunity to hear him, it's well worth your time.
We had a balcony cabin and were glad we did. The weather was nice and we were able to be outside on the balcony much of the time. We saw whales, otters, etc. while sitting on our own deck. We enjoyed the main decks, too, while seeing the glaciers or when entering or leaving a port. But much of the time was spent in our own space.
Whatever you decide, you will be amazed at the beauty that Alaska has to offer. Enjoy planning your wonderful cruise!