I've been in Chicago for one week in last October.
I agree about Central Camera on Wabash : a very nice place from the outside, you can buy film inside, but don't expect to find second hand gear at interesting prices there. I have spoken to Don and he was happy to see somebody holding a film rangefinder camera. I got a free cookie and his business card.
What to see in Windy City ?
- Art Institute of Chicago and the Ryerson and Burnham Library (same building),
- Harold Washington Public Library,
- Union Station (tribute to Brian De Palma etc),
- giant iron sculptures by Calder and Picasso in the Loop,
- Ship Canal and Chicago River banks,
- Astor Street with the oldest houses of Chicago, with some having survived the 1871 big fire and some built by F. L. Wright,
- the view from the top of the Willis Tower,
- Oak Park (there, all that has been advised already above by other posters plus the Post Office : get in and don't miss that architecture gem !). You will go through the poor sectors of the West and will see them from the EL train while riding to Oak Park,
- the University of Chicago sector at the very South is nice enough with a fantastic books shop just in front of the SSL train station on East 57th Street ("Powell's Books Chicago").
Music : good advices above (pay attention to that there isn't music every evening at the "Green Mill" and to that the "Buddy Guy" is very often overcrowded). Also, try to go and listen to a concert by the CSO, one of the best orchestras in the world.
Where to stay ? I've been at the HI Chicago youth hostelling (Wabash/East Congress Parkway) : not much privacy but afterall not that bad if you're on a budget, and very well located in the Loop :
https://www.hiusa.org/hostels/illinois/chicago/chicago
I recommend you to have a drink by night at the rooftop of the "Cindy's" on Michigan Avenue, in front of the AIC :
Nikon S3 - W-Nikkor-C 28mm f/3.5 - Fuji Neopan 400
And you can get married on La Salle Street on Saturdays evenings...
😉
Nikon S3 - Nikkor-H-C 50mm f/2 - Fuji Neopan 400