Enjoy! I'm from Chicago but haven't been back in years but I think below still applicable..
Chicago architecture tour on the water is always what I suggest to tourists.
The museums are INCREDIBLE. To me they are better than the ones in DC. You really can't go wrong with any including Planetarium, Art Institute and of course the Field Museum.
Downtown of course is where everyone wants to be but it's the neighborhoods of Chicago that are so fabulous. The Lutz is a family owned place that's been there forever. Ann Sathers has multiple locations for breakfasts. Chicago is a big breakfast town and after you return you will miss it cause it's just like that here

We do breakfast with more than just buttermilk pancakes LOL Food is really where it's at in Chicago.
Neighborhoods will typically have different fests throughout the summer so you may want to look at some calendar for that. Getting to Lincoln Park or Wrigley should not be hard if you are around Loop.
Tourists typically do Navy Pier, Millennium Park, Willis Tower, etc. I like 96th Fl of John Hancock. They also have a restaurant up there, best drinks ever.
2nd City in Old Town for a show is always fun.