it depends on how old are your kids

to determine whether they would enjoy the Whitepass train - it is mainly sceneries and if your kids are small, they may not appreciate it at all.

For us we prefer the drive to Whitehorse - the first part of the drive (to Canadian border) and beyond, sees pretty much the same scenery you see from the train. I believe there are cruiseship tours going 1/2 way but turn around after reaching a particular scenic spot. We saw tons of tour buses made that turn around.

Misty Fjord floatplane - highly depends on weather and there are mixed reviews on that - you are lucky with good weather, you have great time. you are unlucky with lousy weather, you feel a total waste of money as such excursion is certain on the expensive side.

Juneau, dont know how late the shuttle operates - you need to post a question on the board to ask. Captain Larry's tour - again, mixed review - some see lots of whales, some see nothing. Calm sea versus rough sea. Rainy weather versus blue sky.

You have to remember ONE THING - no matter what you plan, there is ONE THING YOU HAVE NO CONTROL - THE WEATHER. The weather totally determines whether you have a great time, a so-so time, or a LOUSY time.