If you go to the end of Terminal 5? (wherever Delta is at), you can get a good view of the international terminal and the intersection of several taxiways. Actually that could be difficult if you don't have a boarding pass now.
There is a good airplane store in the basement of the Airport Hilton called 'ORD.' They have die cast metal, plastic, and all kinds of other stuff.
O'Hare Hilton Athletic Club:
Located on the lower level of the O'Hare Hilton [note: this hotel is literally in the airport], this full service workout center offers cardiovascular and weights training equipment, a pool, a dry sauna and complete shower amenities all for $9 per visit. Call 773-686-8000 for more information.