I recently stayed at the Fairmont Chicago and found it to be a fantastic hotel. Staff was always courteous and helpful - from the front desk staff at check-in to wait staff in Aria restaurant, to the maid who cleaned my room. The rooms were recently updated, with large flat-screen TV's, beautiful linens, and exceptional toiletries in each room. My room even had a view of Monroe St. harbor. It is truly a first-rate hotel. Location is south of the river and east of Michigan Ave -- as we normally stay north of the river it seems a little out of the way (if that's possible in downtown Chicago), however its location significantly lowers street noise. The hotel has excellent access to Millennium Park, the Aon center (there is a connecting concourse), and is about 4 blocks from shopping on North Michigan Ave. I ate dinner in Aria and it was fantastic! Room service for breakfast was quite good as well. Overall, I'd stay again in a minute if I had business in the loop, or leisure plans in Millennium or Grant Parks. 
