i'll be at lollapalooza all weekend, so will probably not be able to meet you & yours, but if you can make it down to the northside of the city, there is another great street festival going........more neighborhoody & really a good slice of chicago summer life.
it's called retro on roscoe, maybe 5 bucks apiece to get in (the city shuts down the streets to set up stages & so you can mill about in the street), buys you bands & people watching all day. lots of local restaurant food.
these street festivals (there's at least one every weekend all summer) are the main reason i still live in the city.......they're great.
probably wouldn't take you too long to get to this part of town by taxi, or maybe your hotel has a shuttle. or if it sounds interesting & you're into it i could map you out how to get there via public transport.
http://www.starevents.com/retro_fest_LineUp.htm
hope you have a great stay here..........