Lots of what everyone else said about visiting Chicago so I won't repeat it. I will talk about a few things I experienced. Where we were tailgating at North Shore Lot, about a mile from the stadium, was free and fun. A group of NW fans had a 5 foot tall Jenga set made from 2x4's. It was great. During the game we sat in the south endzone and all game there was a huge (400lbs) man who loved reminding us which way Lincoln was. Good natured ribbing was fine and all, but if you are going to dish it out, at least stay to take it. When we went up in the 4th, he dissappeared. It was amazing. I didn't even see him go.
Funny story on the train ride: I know about the panhandling in the city and all big cities for that matter. Just ignore them and they will get off at their stop. A lady is going up and down the ailes and asking for a "Quarter, a dime, a nickel. Anything helps me get a cheeseburger". Reminded me of the guy down in KC plaza. A guy said he had some for her and proceded to pull out his wallet. He fans out his money and pulls out a buck. Panhandler then says "$2 would be even better, that would get me a nice lunch." The guy then puts the dollar back in his wallet and tells her "You should have been happy with the one. Now you get none." She got off at the next stop yelling at all of us but especially the guy.
Best part: Game obviously
Worst Part: Ate at the Purple Pig. Had to seek out a McDonalds afterward just to fill up for 1/4 the price.