I just returned from 11 nights in Chicago attending a conference at the Hyatt Regency and then tacking on some personal time at the end (free stay using Hilton Honors points at the Conrad). I feel your pain with the upcoming tuition bills-we budgeted our trip carefully because we are still recovering from having 2 kids in private colleges in the last 6 years.
The Hyatt is lovely and the staff members were very welcoming. Ask for a room with a view of the river-we were able to see the sightseeing boats coming and going, as well as the Wrigley, John Hancock and other landmark buildings:
Some free/cheap things to do:
1. Among other things, Millennium Park has the Bean and Crown Fountain (the fountains have faces projected on them and spit water periodically to the delight of children below). There are also free concerts in the Pritzger Pavilion in the park on different nights in the summer. The section of the park where these things are located are about a 10 minute walk from the Hyatt. On the day before my conference, I took a free exercise class in Millennium Park (Saturday mornings-Zumba, yoga, tai chi or Pilates) and then stayed in the park to watch the Grant Park Orchestra rehearse for that evening's performance (also free). On a first trip to Chicago last fall, we went to free dance classes that the park has on certain Friday nights-also fun:
http://explorechicago.org/city/en/millennium.html.
2. The Chicago Cultural Center has a free tour guide program called Chicago Greeters. If you book at least 10 days in advance, they will do a customized 2 to 4 hour tour according to your interests-if not, there is also an InstaGreeter program where they have people going brief architecture tours at certain times of the day. If the places that you want to visit are not within walking distance, you get a free transit pass that is good for 24 hours. We wanted to a large farmer's market in the Lincoln Park area, toured part of the Palmer House (a lovely old hotel), and visited a mock-up of the city at the Chicago Architecture Foundation. The Cultural Center also has free concerts on certain days-my husband went to one while I was attending my conference.
http://chicagogreeter.com/
http://www.explorechicago.org/city/...ions/dca_tourism/Chicago_Cultural_Center.html.
3. We visited the Museum of Science and Industry and the Art institute of Chicago-very worthwhile but definitely not free-MOSI has a lot of add-ons for special exhibits.
4. Giordano's was awesome! We hit some great "small plate" restaurants where you don't have to eat a lot, but the tab can add up fast-The Publican, Girl and the Goat, Sable Kitchen.
5. If you have Gold or Diamond status with a hotel chain (as we do with Hilton), you may be able to request that Hyatt do a "Diamond trial" which would allow you to get Diamond status for 60 days. As a Hyatt Diamond, you will have access to the Regency Club lounge, which has breakfast, snack and a decent spread of evening appetizers out-we made liberal use of the lounge food while we were there. You might also want to see how much it would cost to upgrade to the club level. We did a Diamond trial and were upgraded to a lovely suite (this is not a given, as the hotel often fills up with conferences).
6. The Goldstar website has discount tickets for some events, and I think that there is also a discount theater ticket place called Hottix-we did not use either of these.
7. Doing the Chicago wander can easily consume some time and be done for free-it is a beautiful city! Your hotel puts you within an easy walk of the Loop and the Magnificent Mile.
8. The Water Tower Place vertical mall has a great food court and would be a moderate choice for meals-lots of different tasty ethnic food options and very clean.
http://www.leye.com/restaurants/directory/foodlife.
9. The boat tours on the Chicago River are fun-we did Wendella, which was a bit less costly than the tours run by the Chicago Architecture Foundation.
Enjoy your time in Chicago-I fell in love with it-but then, I fall in love with so many places-thus, the reason for the timeshare and my leveraging of hotel points!
This is Chicago. Deep Dish - Giodarnos on Lake/Michigan.
with a soup ... a hidden gem. 
