As a past resident of the Windy City, I can tell you that the traffic and parking hassles have never been worse. So finding a place located within 3 minutes walk from an "el" station is a godsend. With CTA apps telling you when trains will arrive, no need to waste time standing on cold/hot platforms.
With parking spaces being at a premium (and running $4 - $10/ hour) at most popular areas of the city, it would be foolish not to take advantage of public transportation. CTA offers 3-day passes for $20.
If you are concerned about train noise in the apartment, it is hardly perceptible. Ambient sound from fans, music, etc. easily makes the train rumble negligible.
Kathy was a great host, as was Patrick (her poodle mix). She provided a welcome basket of snacks and drinks, access to laundry in the apartment, and responded to minor glitches in a super prompt manner.
She also has free tv services including netflix which comes in handy after a long day of touring.
This semi-basement apartment is nothing fancy and only has 1 separate bedroom and 1 bath. But it is super comfortable, and economical if you're looking for a touring base for a couple or small (<4) group. Futon in living room provides addl sleeping space for 2.
Parking is on the street and Kathy provides a pass for weekday nights. Street parking can be tight but we always found a space on the block. As the train is so nearby, a car may not even be needed as you can get from O'Hare to the apartment totally by train in under an hour. The nearby station (Rockwell) is also elder friendly, being an "at-grade" station. The apartment does require stepping down 4-5 steps to access the entrance door.
I would definitely consider Kathy's place again for future visits to Chicago.