I picked a nice fall day and drove out to Starved Rock State Park. There are a number of trails to choose from there and the geographical features are actually quite interesting (especially for Illinois). This is supposed to be the number one attraction in Illinois. I would rank Chicago first, and then this second. It was really interesting, and the views from up high along the river were nice. It was a nice place to go for a one day excursion to get away from the city and get some fresh air. I was hoping to see some animals (maybe some deer?) but there were so many people, that the animals stayed hidden.
Anyway, it was nice and I recommend it if you want to go hiking near Chicago. Any significant change in elevation is achieved by wooden steps, not a dirt trail. That is a bit of a culture shock for me. I am used to dirt trails, especially in the National Parks. Overall, though, I would say it was worth it. The other Illinois Park I would like to go to is Garden of the Gods, but that is about 6 hours from Chicago, so I need to devote a weekend for that. I don't see myself doing that anytime soon.
I hope you get a chance to go on a fall hike before the snow comes!
Here is a picture from my hike: