Warmco 10000mAh Portable Travel Fan 7-inch, Up to 24H Runtime, Ultra-thin Quiet Rechargeable Battery Powered Desk Fan with Digital Display for Camping, Office, Bedroom, Cruise Essentials

I don't think Chicago Union Station is difficult. I would add to your list making sure you wear (and not just bring) comfortable clothes, and dress in layers so you can add or remove based on the temps you encounter. I also always bring a fan like this https://a.co/d/04y1ngwZ You mentioned trying to sit in the upper level, trains east of Chicago don't have an upstairs. And when you buy a coach ticket for the trains on the western side of country, you explicitly choose upper level or lower level at the time of purchase - it's not a choice you get to make onboard