We keep talking about how much we'd like to do it, so let's start making some firm(er) plans for a trip to Chicago.
We'll carpool to Michigan City, IN, and take the South Shore Line into the city. The drive there will take about 2 hours, and we should probably plan on catching the 10:30 AM (Eastern) train. That'll get us there around 11 AM Central. I'm hoping to have everyone who's riding along picked up by 8 AM. If there are more than 4 of us going, I'll rent a minivan.
The South Shore costs $8.50 each way (so $17 round trip). You can pay with a credit card at the station, or in cash on the train. When we get to the city, we'll be taking the L to a couple of different places. If you have a credit card with an RFID tag, you can use that to pay for CTA fares, otherwise you'll need to order a Ventra card. Do it early - they've been known to have issues with order fulfillment. You can also buy one from the kiosks at the station - that might actually be a better idea. Put $5 worth of transit credit on it - that'll be enough to cover two rides.
We'll take the South Shore to the 11th St station, and visit the Field Museum, part of the Museum Campus. "All-Access" admission is $31, and it'd probably be a good idea to buy it ahead of time.
Someone said they wanted to go to a food festival, so after that, we'll be visiting the Taste of Randolph Street festival in the West Loop. We'll take the L from State and Roosevelt (about 6 blocks west of the museum) to the Morgan St station. The festival is a block south of there. Admission is technically free, though they request a $10 donation at the gate.
Once we leave there, if it isn't too late in the day, and if people aren't feeling homesick yet, we could find a few other things to do. We'll be pretty close to the Sears Tower if anyone wants to see that, or we could just check out some of the stores or other attractions throughout the Loop. Otherwise, we'll take the L back to Randolph and Wabash, and get back on the South Shore at Millennium Station to head back home.