Been a long time since I was in Chicago, but I really liked:
 
Al’s for an Italian beef.  White Castle for a couple of burgers (only have em frozen in Maryland – it’s a short walk from Midway).  Lou Malnati’s for deep dish pizza.  Billy Goat for one cheezborger cheezborger (not that great, but I’m a nostalgia/SNL chump).  Portillo’s for a Chicago style hot dog (no sport peppers, I’m a panty-waist).
 
I know it’s a short trip fpr you, but if you have time, the Field Museum is excellent.