I did Alaska on Celebrity - I got 3 nights longer and took one extra person and a bigger room and a veranda versus what I had booked on
DCL. I'm a huge DCL fan - going on my 9th cruise next month and our Grand Slam cruise - but I don't regret not going on them for Alaska. For me, that was all about the scenery and the ports. We had a great time and having the balcony was a huge bonus on the day we sailed near the glacier. The decks were packed so it was nice to have a balcony to go to. The onboard entertainment was a disappointed, but not such a big issue for me with Alaska.
BUT - not sure if I would sail a huge RC ship to Alaska. That is a lot of people to compete with when you get off for excursions, and from what I've read, I don't think on that particular ship there are a lot of good places to view the scenery if you don't have a balcony. If I were you I would look for another cruise line besides DCL but a smaller ship and get a balcony.