Thanks for the input. I decided to go with the safer route ant take the later plane- nothing to worry about that way. It also gives me time to grab dinner at O'Hare- my (usually good) patience gets thin when I haven't eaten and air travel is not a good time for short patience.

BTW- when i called AA to make the change, I chose the "call back" option. Somehow, when I got the call back I was connected to someone at the executive platinum desk who was expecting someone else. The agent did go ahead and help me, so I may have gotten better than usual service. Took care of the change quickly, but tried to charge me extra when I selected an MCE seat (my original reservation was main cabin plus) Once I pointed this out she "checked" and agreed I didn't have to pay extra. Color me cynical but gotta wonder if the attempt to charge me more was an honest oversight or whether they figure some people wouldn't know they shouldn't be charged and try and get away with it.