I'm originally from Chicago. I have a friend about to visit and asked me for tips. Here are snippets from our conversation that may help:
First off, here is where you want to stay:
Downtown Chicago Hotel - Palmer House Hilton, IL If you don't have a Hilton account, create one because they usually have member only prices. I've stayed here for as little as $100/night.
www.palmerhousehiltonhotel.com
If you want a very special dinner, I highly recommend Gejas:
https://gejascafe.com/
If you want to try the best deep disk (I actually prefer thin crust), go to the original Gino's East on Superior:
https://www.ginoseast.com/magnificent-mile
162 E. Superior Street, Chicago, IL.
Another awesome place to eat or drink is The Signature Room on the 95[SUP]th[/SUP] Floor of the Hancock Building
https://www.signatureroom.com/
If you stay at the Palmer House, you can walk to The Bean and Buckingham Fountain. Great photo opportunities. Buckingham Fountain has a light show at night.
If you want great German food not far from the hotel, check out The Berghoff:
https://www.theberghoff.com/
In all seriousness, if you have the time, The Museum of Science and Industry is amazing. They have a coal mine and captured Nazi sub that you can tour:
https://www.msichicago.org/
You have two type of architectural tours: one that takes you onto the lake and one that does double decker bus. They are both great photo opps.
Kinda expensive but the Willis (Sears) Tower in the south loop is always outstanding. Great photos from the top - especially at night.
Literally right next door on Wabash to the Palmer House is Miller's Pub. Excellent food:
http://millerspub.com/
134 S. Wabash Avenue Chicago, IL 60603
Comedy, of course you have Second City:
https://www.secondcity.com/shows/chicago/venue/chicago-mainstage/
Shopping: Michigan Avenue aka The Magnificent Mile
If you DO want beach, you can always do Oak Street or any of the others:
https://www.timeout.com/chicago/things-to-do/chicago-beaches-guide
Don't forget Navy Pier either.
https://navypier.org/
This is just off the top of my head - I didn't even go to Little Italy, Chinatown, Iranian Village, Koreatown, Greektown, etc. for places to eat.
Don't forget the theaters too:
https://www.chicago-theater.com/