I travel to O'Hare every week with four co-workers, and we are always able to get a minivan cab with no more than two or three minute wait. We've been going since July, and we have never not been able to get a minivan cab at O'Hare.

Once, we took the Airport Express and found it to be more expensive and less convenient. Hailing a cab on the Loop and going to ORD is $50 for five people with a good tip; Airport Express was $70 for the five of us, not including tip, and we had to make two stops along the way. For three/four people or more, I'm not sure that the Airport Express makes sense as long as you can all fit into one cab/minivan cab.