There is a book called Guide to Chicago's Train Stations. It details many of the older suburban stations, including ones that were demolished decades ago. Some of the suburban stations built in the 1800's and early 1900's commonly included multistories, a lot of agent office space, living area and even expensive decorative architectural features like clock towers and pointy turrets. A possible reason for living space in these stations might be the way railroads operated at the time that required a lot of people working at stations along the line, especially on the busy suburban lines, I could see the living space being for higher ranking people that were in charge of all this, where it would also be convenient to have them live close by in case of emergencies. Also lots of buildings were built to look like big houses because it was the style at the time. This stuff probably went out of favor because it became expensive to build and maintain all the extra space, and railroad operations changed to reduce the number of people needed at suburban commuter stations, for example dispatching handled from central locations and signals instead of by station personnel.
I would like to know about the abandoned Rock station in this photograph:
www.railpictures.net/viewphoto.php?id=240105&nseq=1