I'm coming to Chicago from the southeast on I-94 this weekend. Is there a place to leave my car for the weekend, somewhere close to a public transportation depot? I'm considering leaving behind the car and using public transportation until I go back home. If there is such a place, what will it cost on the weekend?
Basically your best bet would be to use the Northern Indiana Commuter Transportation District's South Shore line to take a train to Chicago.
Personally having driven on both I-94 and I-90 South East Chicago, Gary, and Hammond might not be the best places one might leave a car, so I would suggest going to South Bend as it might be a little out of the way, though not much and you can catch a train from there to Chicago's Union Station.
You can check the schedules online.
Many options. Here is one - I live right by it. Parking garage on Maxwell and Halsted. It's about 8/day. Limit technically 72 hours but never had a problem. CTA blue line short bus (#8 Halsted north), cab, or 12 minute walk. CTA stop is UIC-Halsted, will get you anywhere you need to go.
Ps - Maxwell and Halsted is directly off 90/94/55/290 so basically every expressway.