Lou Malnati's is pretty good . .but if you want what I think is the best pizza I've ever had . and what GQ called the best pizza in America:
Great Lake Pizza in Andersonville. (
http://www.yelp.com/biz/great-lake-chicago)
If you want the best burger hands down (be prepared to wait like 45 min)
Kuma's Corner (
http://www.kumascorner.com/)
If you want some sick ass mexican food:
Mixteco Grill (shitty sign, amazing mole:
http://www.yelp.com/biz/mixteco-grill-chicago)
You like beer / montreal style brisket:
Hopp Leaf (
http://www.yelp.com/biz/hopleaf-bar-chicago)
Best beer selection in chicago, along with some of the best food.
Best Chicago Hot Dog:
Hot Dougs (
http://www.hotdougs.com/ <-- fucking crazy amazing)
Shii . . what else . . .
Best adult bar in chicago if you like to drink and think clubs are lame:
http://www.longroomchicago.com/
Hope you have fun!
EDIT:
Oh this would be a good time to pimp the non-profit blog me and a few friends write for:
http://www.chicagogluttons.com