We we lucky enough to get on (at Chicago & State) the car right in front of the flatcar with Santa's sleigh, meaning it was still standing still when we got out at Addison! In previous years we've had to run to check that out, or make due with a blurry shot as it sped past out of the station (I think they hold this in each station all of an extra 5 seconds over the usual stop time).
If you've never had a chance to ride the Santa Train ... the interiors are all decked out, including "funny ads" (and Elf-centric jokes), special upholstery, and "helpers" handing out candy canes! This is an annual volunteer project by the CTA workers, who decorate and run the train on their own time ... which is a nice "gift" for their riders.
My Wife says the best part of it is watching the folks in the stations who aren't expecting it ... as it's elaborately decorated both inside and out, and it can be quite the surprise if all you're looking for is getting from point A to point B!