From: Northwestern Georgia, USA
MUST: Science and Industry Museum U-505 exhibit. It's just been re-done, and where else can you tour a Type-IX Nazi U-Boat? BOOK AHEAD for tickets to the U-505 though
Field Museum has a current special exhibit on PIRATES. Not too bad, sorta kid oriented but I liked it
SEARS TOWER has a new observation platform called THE LEDGE; it's a glass box suspended over the street you can walk into and look straight down. Apparently it's WILD, I haven't seen it, but I plan to. Check out the photos online.
SHEDD AQUARIUM is very cool if you don't have a slick local aquarium. It's first-class! Check Bears schedule though, don't plan on going during a Bears game (same for the Field Museum, they are right next door to Soldiers Field)
LINCOLN PARK ZOO is free, and a good way to kill a couple hours downtown if you have some time. You can just hit whatever animal highlight you prefer.
Strolling around MILLENIUM PARK is cool; the fountain, the gardens, the bean sculpture, and the other stuff, check out on the web
ART INSTITUTE: We have one of the world's top 10 art museums. May or may not be for you, but if you like Art, must see. New addition JUST opened.
BASEBALL: Cubs and Sox if you like Baseball, not sure where you are from. I am a Cubs Season Ticket Holder, I think my September games are spoken for, but maybe someone will bail and I can get you a pair.
HOTELS: This depends entirely on your budget, and how important location or updated rooms are to you. If you don't have a car (and you shouldn't bother), there are a ton of good alternatives downtown. Parking is very expensive, unless you are driving to get here do not bother renting a car.
PM me for more, including eats, I currently live in the city of Chicago (near Evanston)
This post gives me contrary feelings about QBall - he has sense enough to be a Cubs fan, but he's gonna walk into that glass box that's 103 stories (1,000 feet) above pavement? No way! Give me good ol' terra firma!