Chi-Town Recs

Hello everyone. I have finished my exams--yay!--so now I can focus on my plans for the weekend. We're headed to Chicago this weekend, where we'll have a quick visit with my Nana, plus my parents, Lea, and Ryan will attend a wedding.
So, my question is this: What's your favorite thing to do in Chicago? I've visited Chicago throughout my entire life, so I've already experienced most of the tourist-y attractions. The Chiago Diner is already on the agenda, but other than that, I am open to any and all suggestions!

Thanks in advance!