There are several great museums in Chicago, however, my favorite, hands down, is The Field Museum. The Field Museum is my favorite solely because of "The Genius Hall of Dinosaurs".
I could stand in Dinosaur Hall for hours looking at the dinosaurs. There is just something about being in a room with all these massive dinosaur remnants that makes you appreciate the complexity of earth and life.
Dinosaur Hall is part of the Evolving Planet exhibit. The Evolving Planet exhibit is included in The Field Museum’s basic admission ticket.
Below is a quick video that I took from the center of "The Genius Hall of Dinosaurs". There are additional smaller dinosaurs in other rooms, these are just the large fossils that are too large for average sized ceilings.