What is there to do in Chicago?
Do everything Ferris Bueller did on his day off.
There's so much to do - it will really depend on what interests you. There are great museums and parks, there is a good zoo and a good aquarium, the views from the Willis Tower and Hancock Building are fantastic, Navy Pier is fun, there are architecture boat tours on the river that are way cooler than they sound, you can shop on the Magnificent Mile, there are great restaurants, you can see some good shows, and you can hang out at a beach on the lake.
There are too many things to see and do for me to list here. Since I don't know what interests you, please go to a public library (or bookstore) and find a tour book on Chicago, and use a search engine to find listings under "Chicago Events" and "Chicago Tourism." You will see listings of all kinds of things to see and do, including calendars of special events.
Grant Park Music Festival West Fest Pitchfork Music Festival Lagunitas Brewing Company free brewery tour with samples included, Sad you miss the June bike ride. https://www.youtube.com/watch?v=rAFnYAMuQP8
You'll be glad you're from LA once you get there and back. I can say this as someone who's from chicago and reside in LA.
sadly, a big comic con will be there in August. That's the only reason I have ever gone there.
freeze and fart