Congrats on your invite!
when I went to ico 2 weeks ago, I also decided to do some sightseeing the day before my interview as well. I traveled by subway to save money ($2.25/trip) and since I was visiting chicago on my own, I only went sightseeing during the day. I would say that millenium park is a nice tourist spot, they have very interesting sculptures. In addition, the chicago art institute museum (which is literally across the street) offers a student discounted admissions fee. Although, i've heard that if you visit a public library in chicago and sign up for a library card you can get a free ticket for the chicago art institute museum. Another place I would suggest to check out is the john hancock building, you can get a great view of the entire city (there is admissioms fee, not sure how much though). Lastly, get a hot chocolate at the ghiardhelli chocolate store! (which was pretty busy when I visited)
all the places i've mentioned are on the "magnificent mile" which is a really long street that has a bunch of shopping centers as well. I don't have any suggestions for places to dine though since I pretty much bought snacks throughout the day... Plus I didn't feel comfortable eating at a fancy restaurant by myself lol
Scholarship Access: Becoming a Student Doctor course