I remember going with my dad to ORD in the 70's, and we'd arrive early to pick up friends or relatives from the airport so we could watch from the observation deck. It was open-air as I recall and had those coin-op telescopes you see at touristy places. What happened to it? It's too bad that one of the world's busiest airports doesn't have any decent, legal places to spot.
Knowing Mayor Daley's seeming disdain for aviation--ie:the Meigs situation--I'm not holding my breath on any deck returning anytime soon.