I wasn’t in Chicago long to be able to eat at all the restaurants (Chicago has many!), but here’s what I do know of…some I can vouch for, others are Chicago classics:

Pizza: Try Deep Dish (a chicago invention) at the original

Gino’s East (633 N Wells St) make sure you go to the one on Wells because everyone brags that they’re the ‘original’ deep dish…

http://chicago.citysearch.com/profile/3663723/chicago_il/gino_s_east.html

Breakfast:

Lou Mitchells’s (great pancakes and waffels)
http://chicago.citysearch.com/profile/3740426/chicago_il/lou_mitchell_s_restaurant.html

Fresh Juice:

The Fruit Factory
http://chicago.citysearch.com/profile/41454728/chicago_il/the_fruit_factory.html

Prime Rib:

Lawry’s The Prime Rib

http://chicago.citysearch.com/profile/3667096/chicago_il/lawry_s_the_prime_rib.html

Coffee and desserts:

Julius Meinl Cafe (brags to be the finest outside of Vienna)

http://chicago.citysearch.com/profile/35397155/chicago_il/julius_meinl_cafe.html

I hope this helps! Let me know where you go!

Bon Appetit!