Chicago has so many hotel rooms that you can get great rates through hotwire when there doesn't happen to be a huge convention in town. A quick look just now showed a 4.5 star hotel for $121 a night, and a 3.5 star hotel for only $74. We've booked hotel rooms this way through hotwire, in both of these search areas, 10+ times and never been disappointed in where we landed. These locations are really nice... you're going to be on or within 3-4 blocks of Michigan avenue, close to Navy Pier, etc.

If you are booking a specific hotel then you could look a little further south near Millennium Park but that search area for hotwire is a little too big so we usually don't use hotwire for that.