We did a 7 day trip last year early May - Vancouver to Vancouver......, Juneau, Skagway, Glacier Bay and Ketchikan. All we had was rain and fog and it was so bad that we never did make it in to Ketchikan as the seas were very rough and Ketchikan was fogged in.
I don't think you are going to see anymore snow or ice early in May, except maybe in Skagway. I have seen pictures of the White Mountain Pass Railway excursion showing lots of snow and it was beautiful.
Mind you living in Northern Ontario, we get enough snow and ice all winter so we couldn't have cared less whether we saw snow.
Glacier Bay was wonderful, but comparing pictures I took back in the 80's to the ones I took on the May cruise you can see just how the Glaciers are receding.