Returning the car: There is free street parking within a few blocks of 641 W Grand in every direction. However, be careful about loading zones, parking under bridges (always no parking zones, even if there is no sign), and metered zones. The gravel lot off of Hubbard is a no-parking zone as well.
Free street parking is generally found on both sides of Grand Ave, both sides of Des Plaines north of Grand, but only one side south of Grand, and both sides of Union Ave.
Be careful about Ohio Street. It looks safe to park, but it is a no-parking zone from 7am to 9am each day. If you are returning the car late at night, it will be ticketed in the morning. Park there only if you've texted me and I've responded that it's ok. Much appreciated, thanks.