We did the NCL Star and went to Tracy Arm and then again on the NCL Pearl and did Glacier Bay. To me, there was a big difference in the beauty of the two places. Glacier Bay was absolutely amazing with more snowcapped peaks and glaciers.
We got right beside Sawyer Glacier (google it...is amazing)for about 1 hour, the captain cut the engines, and all you could hear was the cracking of the ice and we saw ice calving. When we went to Tracy Arm, we couldn't get very close because of the ice flow (we went in July.) When I was in Tracy Arm, I thought, 'wow...this is beautiful' because I didn't have anything to compare it to. When we went to Glacier Bay, I saw the difference and would only choose cruises with Glacier Bay in the itinerary.
Considering
DCL was 3000.00 more for the same veranda type room, you didn't go to Glacier Bay, and the NCL ships are much better equipped with dining rooms and lounges with floor to ceiling windows for viewing, we booked the NCL Pearl next year again for Alaska.
Something to keep in mind, when you are on the Alaska cruises, you never know what beautiful site will be around the corner or when you might see a whale or other wildlife. On the other DCL cruises we have been on, you don't watch the water or the scenery as much so you don't think about having public areas with lots of windows. It was really nice to have so many areas on the ship with NCL that you were always able to be watching for wildlife and viewing the scenery even when playing bingo, doing trivia, eating, etc. The DCL ships don't have that.
We love DCL and we are Platinum, but for Alaska, we choose NCL.