Hubbard Glacier - Great. Saw some calving (ice falling off the glacier with "booms").
Here's where that Alaska Coupon Book comes into play.
Answer: You ONLY need your cabin key. No passports or picture id!!! Canadian customs and emigration did not check anything. When you return, you only have to show that cabin key.
The downtown is a 45 minute "force march" according to the bus driver. To do that at night in an unfamiliar place....? Was here from 6:00 pm to midnight. Again, would have liked to arrive in daylight for a full day. I would suggest the Holland America first go to Victoria from Seattle then sail up to Juneau.
Bus driver took us on a impromptu tour of the city on the way back to the bus. There is a small tourist shop at the dock for the "made in China" souvenirs or post cards. You need Canadian postage and not US stamps!