Oh man, that's a tough question. If I had a day, I would do breakfast at Goddess and the Baker, lunch at The Purple Pig and dinner at Oriole. Some of my favorites activities were the Skydeck, Robie House tours, and the River Architecture tour. They are all over Chicago so you might have some time constraints but I'd definitely squeeze all those things into a day.
You took the L after midnight 😮 you are a brave soul , im from Chicago and wouldn't dare do that ! Im glad you were safe , it still just surprises me that people actually fly here to visit 🤯