re: online checkin with Amtrak segment
I have a flight tomorrow that is preceded by a segment originating at ZFV. Was able to check-in online successfully for all segments. As for the Amtrak segment, it just prints out this faux boarding pass with no Gate number.. and a blurb saying, "CK-IN AT TICKET COUNTER".
So, perhaps CO has fixed the problem of online check-in.. but as far as I can tell, I'm good to go. ^