They will not let you linger. They will force you to park. You can get away with it at arrivals, sometimes, but then your parents have to go from baggage back to arrivals with their luggage, which may or may not be easy for them.

ORD does has a cellphone lot (free, where you pull in and wait until you get the call that they're on the curb), which is actually pretty convenient but not if your parents are like mine and not cellphone-enabled.

My father always meets us at the "Kiss N Fly" lot, where you can just park and wait, which would be ok except that there are almost *no* signs from the terminals that indicate where the lot may be, and its really stupid name makes it highly embarrassing when one needs to ask for directions, due to the lack of signage.

But it may be an option. But only if you have time to let them know that ahead of time, or can leave a message on their phones for when they arrive.

What crush-onastick said: if they've got a cell-phone, parking lot F is totally the way to go. If not, I'd recommend hourly parking (lot A): I think it's $4.00.