It's worth a trip to Chicago just to have a burger at Kuma's Corner near the Blue Line stop on West Belmont. It's about a 30 minute ride from ORD and is easily walked (less than a mile) to from the Belmont Blue Line stop or you can take the eastbound Belmont bus.
Service at Kuma's is good, the heavy metal music is blaring, the beer selection is top notch and the burgers are served on a pretzel roll. There are many topping and combo options on the menu.
One caveat - the lines to get a table can be long. One trip I made on an early Sunday afternoon had a two hour wait. I was lucky enough to grab the solo bar seat available on this visit. Other visits were not so bad for the wait and were mid-week mid-afternoon stops. I often plan my trip from downtown to ORD with a stop at Kuma's for a burger, beer and a dose of heavy metal (the heavy metal is really not my style but it fits this place perfectly).