This is a fantastic place to stay if you're in downtown Chicago. It's just off of north Michigan Ave. where there is PLENTY of shopping to be had, within 5-7 minute EL stop at State St. and Chicago Ave., a couple of blocks from Lake Michigan and Lake Shore Drive.... it is just a great location.
The hotel staff could not be nicer, more friendly or helpful. From the doorman, to the front desk attendants, to the Concierge, to the bellman, just the best. The room we had was on the 9th floor and one could see the beach of Lake Michigan between the buildings with the Drake hotel across the street. The bed was extremely comfortable, loved the shower that felt like a waterfall with the fixture in the middle of the ceiling.
The only thing I would not recommend is to pay $50 for overnight parking. There are other less expensive options and directly across the street at the Drake hotel is parking for $35 overnight. Other than that, you will be well pleased by staying at the Knickerbocker hotel.

We stayed at the Millenium Knickerbocker hotel for 7 nights, in a 2 queen beds room. Room: the room was spacious and spotless. Our beds were super comfortable; I could have taken mine back home, along with the soft bed sheets! Only downside: walls are a bit thin. Bathroom was beautiful and with plenty of amenities. However, there was only 1 bathrobe, even though we were 2 (we did not ask for a second one).
Funny detail: take a look at the mini-bar... you can find everything in it. Beverages, cheese crackers, toothpaste, toothbrush and even an "intimacy kit" (containing condoms, towelettes and lubricant gel). Very thoughtful of the management :)))
Staff: One evening we had a problem with the internet connection; it was promptly taken care of. Staff was very polite everywhere, from front desk to breakfast room.
Breakfast: you can either order from the menu, or take the buffet (approx. 20 USD). The buffet is OK, however we would have liked a wider selection; e.g. there was no cheese (except from Philadelphia) or ham. But, everything was tasty and of good quality.
Dinner: we dined in our room one night, food was good (tomato soup was delicious)
Location: OK, indeed it is not exactly downtown but like a 15 mins walk to the Millenium Park. The nearby (5 mins walk) Rush street is full of restaurants and bars, so it is not like you have nothing to do in the evening. And it is a very upscale and SAFE area (for me this is more important than being exactly downtown). Excellent for shopping too, just around the corner from Michigan avenue, where the Magnificent Mile begins. Plus, only a 3 mins walk from the John Hancock Center. The panoramic city / bay views from the JHC 94th floor observatory are the best, and the lines are much shorter than those for the Sear's tower Skydeck. Night view is also a must, and if you are there on Wednesday or Saturday evening, you will also enjoy the Navy Pier fireworks show; it looks even more spectacular from the 94th floor.

By dumb luck we found the Knickerbocker and feel like we hit the jackpot. EVERYONE tried very hard to be helpful and the location was super. Rooms are clean, comfortable and quiet. The hotel was willing to match the price found on Hotwire, which was very reasonable for Chicago.
For breakfast try the Oak Tree ( located at 900 Michigan Ave.). This was suggested by one of the staff and we liked it so much we ate there everyday. All rolls, muffins,cookies are made there.
We will definitely return to Chicago and the Knickerbocker.

We stayed here for 4 nights at the end of April and overall found it a very nice hotel. It was certainly good value at $420 (prepaid). Yes the room was very small (I'm sorry now reading other reviews that we didn't go for an upgrade) but it was comfortable and had everything. I did find boots under the bed (that weren't ours) so housekeeping might not be as thorough as one would hope! It was the first scorching weekend and I noticed the A/C wasn't fantastic but it worked. Liked the bar for a cocktail before going out, it had a lovely old fashioned feel to it and the bar staff were very friendly. The concierge was excellent, couldn't do enough for us and the doormen/porters were good fun with spot on recommendations. We thought the Knickerbocker breakfast buffet was very good and the doormen sent us to a FAB place nearby called TEMPO when we wanted a nice Sunday brunch. It's an old hotel (I don't know what the rooms were like before) with a bit of welcome character - the only 'surprising' section was the check in desk, it really let the lobby down but perhaps it hadn't been renovated yet? Great location - near the beach if you get sweltering weather like us and a perfect base for sightseeing. We never used room service or looked to eat there aside from breakfast so didn't even notice what time services stopped. We just wanted a comfortable, clean & convienient base from which to see the city and the Knickerbocker ticked those boxes. If you like your meat Fogo de Chao (a few blocks away) was EXCELLENT, well worth a visit. Also a Boat Trip through the city is a MUST.