In terms of Chicago, lots to see and do. It really depends on what you're interested in. Obvious you have the Sears / Willis Tower and the John Hancock Center (now called 875 North Michigan Avenue) if you like tall buildings. A good way to see a fair bit of the city is to do a river cruise. There's a few to choose from but I'd suggest doing one that also includes Lake Michigan. The Goose Island Brewery / Tap Room tour is enjoyable if beer is your thing. The Art Institute of Chicago is also well worth a visit.

The Blue Line from ORD will take you downtown relatively quickly. Of course there's also ride share options as well as taxis. Ride share doesn't pick up in front of every terminal at ORD now. You need to go to a designated pickup zone.

Union Station is worth a visit for the architecture, particularly if you're a fan of The Untouchables.