LogFAQs > #972621048

Catch a game if you like baseball. Wrigley if you like the history and have some money, Comiskey if you want a good bang for your buck.
Check out the Museum Campus. Can spend an entire weekend there alone, tbqh.
Water taxis and river architecture tours are nice. There are trolley tours too, but Ive never been on one.
Eat.
Catch a show in town depending on when youre in and what fits your fancy.
Lincoln Park Zoo is a solid free-entry option.
Ive heard that the mobster tour is fun if thats up your alley.
Mag Mile if you like shopping, I guess.
Sears Tower or Hancock (come on, mods) observation decks for a damn good view.
Navy Piers worth a visit if you had a week in town, but better options are above for only a couple days.