Good answers here so far. I'll fill in a few details if it helps any...
#1) Shorter daylight, potentially cooler, and MUCH potential for windy weather. More small boat excursions are cancelled in September than all the other cruise-season months combined. If you're sport fishing, whale watching, etc. you could be in for a cancelled excursion or some choppy/rough weather. Our fall storms usually begin rolling in during September. Then again, September can be gorgeous too... none of us locals have much control over the weather! ;-)
#2) The areas near the glaciers have their snow most of the summer, and I usually begin seeing the first NEW snow of the season in Tracy Arm and Glacier Bay in September.
#5) Just a note that "Tracy Arm" and "Sawyer Glacier" are the same area to cruise. I'm always a fan of the small-boat excursions into Tracy Arm - Adventure Bound, Alaskan Marine Adventures, etc. - instead of the large ship cruising the teeny fjord, but either way, you'll love it!
Hope this helps some!
Happy Alaska Travels.
1. Anyone sailed in September before? What are the disadvantages (besides shorter daylight hours and potentially cooler weather) of sailing this late in the season?
2. Being September and past the summer months, will there be much less snow on the mountains surrounding Glacier Bay, College Fjord, etc?
5. We have several cruises to choose from. Do any of you consider any of the following glacier cruise days significantly less impressive than others? - Glacier Bay, College Fjord, Tracey Arm, Sawyer Glacier, Hubbard Glacier?