Chicago Restaurants??

Ok, all of you Chicago residents and Midwesterners, it is time for my annual weekend Christmas shopping trip on Michigan Avenue. I have been placed in charge of dinner reservations, and need some recommendations. Our hotel is on Michigan Ave (I think it is the Four Points Sheraton Downtown/Magnificent Mile). I think we'd like to have one casual night, and one "big-night-out". I will be with two other ladies.. can't wait to hear what you come up with!
Amanda K in Miami