Thanks for the suggestions. As far as the trip to Milford Sound, we are leaning towards driving, so appreciate the advice, and will likely look to spend a night in either Te Anau or at the Milford Sound Lodge to try to break up the trip and maximize our time there. Leaning towards something like 3 nights in Queenstown, 1 night in Milford or Te Anau, and then 2 nights in Wanaka or Arrowtown. As far as the glacier walk, yeah, we'd been considering that too, so may look at that as well. Milford Sound was higher on our list, as we live quite close to glaciers (i.e. are driving distance to plenty of glaciers in the Rockies, including the Icefields Parkway and Jasper), but would love to see that too. I've used crampons and ice axes before, but definitely wouldn't be carrying our own gear and not familiar with the area, so would likely need to go with a guide or tour company.