Hi Priscilla
How timely you should ask. We have done two Alaska cruises and I am in the process of editing together the video from both of them at this very moment. We did the glacier helicopter excursion out of Skagway. It was magnificent. One of the highlights of our first cruise. The ride up to the glacier and back was sensational. Walking on the ice was fun and I got some interesting video, but you wouldn't miss a lot by not doing it. I strongly recommend the helicopter trip. Can't comment first hand on the float plane version but would imagine it would be great too. You probably go farther but also faster and you can't get up close and personal like a helicopter can. I'd opt to do the helicopter again before I'd book a float plane. We had a float plane booked to watch bears on our last Alaska cruise on Mariner but the weather didn't cooperate and we didn't get to do it. On that trip, the float plane landed on an inland lake and we were to get out and take photos. We were all reminded that if a bear starts chasing us, it matters not who is fastest but only who is slowest. Warmest regards from both of us.
Pat