An alternative to B&B, and VRBO (both viable options) is Priceline. With a daughter in Chicago I travel there often and as long as it's not a super busy week you can usually get a great deal using the "Name your own price" tool. I have stayed at places like the Hyatt Regency (fab hotel) for under $100 a night. Granted the parking costs $45 a night unless you're willing to walk to get the car. The same tool can work for different areas of town and different star levels.

Dolfer