I would second most of what Gardyloo said except the 26 Glaciers tour. I would do one by Major Marine for a few reasons:
They spend more time at a glacier waiting hopefully for it to calve (26 Glaciers is more concerned with pointing out - in a distance - 26 glaciers)
They are usually less crowded than 26 Glaciers' boats (at least in my multiple trips and seeing the crowds on the Phillips/26 Glaciers boat
There is a Groupon-like 50% discount through the KTUU Anchorage website for the Major Marine trip.
No problem on the Major Marine front. Cheaper is better, too.