I have been passing through Chicago O’Hare lately. It is not on my list of favorites. The dense crowds make it exceedingly difficult to quickly and pleasantly navigate, particularly in the low-ceilinged, narrow halls of Terminal 2.
Terminal 2 however has a hall of calm where it is possible to relax and even sleep, away from the crowds, announcements and popcorn vendors. It serves as a connecter between concourses E and F roughly between the Delta Sky Club in E and the United Club in F. There is a separate connector earlier in the terminal but is less quiet and with less seating.
With the mobs in the airline clubs, this may be the most restful place in ORD.