I wouldn't take a 1 year old on a glacier tour. In fact they may not allow it.
The question about whether it is worth it is always a personal one, but ask yourself this question...how many times in your life will you be able to visit a glacier? Some things are worth doing just because it may be your only chance to ever do it.
As far as train excursions go, if your cruise stops in Skagway I highly recommend the White Pass Railroad tours.