If you would rather book a standard hotel, the blind-booking websites Hotwire and Priceline have proven themselves to be promising sources for discounted rooms in Chicago (and elsewhere). These two sites won't name the hotel (or airline or car-rental company) you're working with until your credit card has been charged. For Priceline, try a lowball bid, using BiddingForTravel.com as a guide. For Hotwire, be aware that the deepest discounts are generally for hotels that it rates "four stars." You'll find the most eye-catching deals by clicking on the "Deals" tab on the site's homepage.
Of course, you face some uncertainty about where you're going to stay if you opt for either short-term rentals or blind-booking sites. You may want to instead go for a sure thing. Consider Budget Travel's picks for affordable, independently owned lodging with some personality, with doubles starting at $99 a night.

