Anyone arriving at O' Hare - - who has not been to that Chicago airport frequently, quickly gets overwhelmed because of the constant construction changes in the airport infrastructure. So if I were in your position, I would 'hold your friends hand' ASAP. I.E., meet that person as he / she disembarks from the plane but via the baggage claim area.
Placing that person on the 'EL' / CTA system (by themselves) is too overwhelming for them. So pay the parking lot price for the benefit of an early trysting place and then both of you will have peace of mind.
After all, they bought the airline ticket to visit you, right? So spend a little money in parking fees for their benefit.
Carter Glass,
Wheaton, IL