OutdoorAlaskan

You can always purchase a cheap plastic poncho to throw over anything. I'd shop REI and sort by your budget.

Hiking the Matanuska Glacier is WAY out of the way. Do the trail along Exit Glacier just outside Seward, then you can hike on Harding Icefield at the top. ALSO it cost money per person to head out to the Matanuska, I think it was around $20 a head, where as Exit is free.

I've never had a problem getting a group to sit together when traveling coach on Amtrak.