So I called Amtrak and added on the bits betwwen Detroit and (what? Birmingham? whatever that station close to the hotel is). They issued two new tickets for just those segments, since I got special time-bound discounts on the initial ticket and re-booking would have cost a lot more. Indeed, adding those segments means the whole trip will cost slightly more than it would have had I'd known to do that from the start, but if I'd waited until all the information was in I might never have got around to actually doing it so it's probably all just as well.
I also had a delightful thought about what we can do with our time during the layover in Chicago between trains instead of just sitting there in the station: chasophonic, chirosinger, and I can crack our cases, get out our gitfiddles, and do some tunes; then we can send the lovely and radiant bonz_lizard and mizzlaurajean around with hats to gather some spending money. Nu?