In Skagway during the first cruise of the season last year we did the helicoptor over the glaciars which then left us at the dog camp for sledding. We were told that the ice at the beginning was the best since over the weeks it would get mushy and they would have to relocate their camp often. It was a day full of sunshine while there, the view was incredible from the helicopter of the snow-topped mountains. of course there's always the possibility of a cloudy or rainy day when the copter wouldn't be able to get off the ground. normally dog-sledding is available at both juneau and skagway so if you're not able to do it because of weather at one, perhaps it'll be a beautiful day at the other!