Great Location
I think I have stayed at everyone of the Starwood properties in the Chicago area (well, maybe not everyone . . . but a lot). The Westin Michigan Avenue is just a great location. It is really a business travelers hotel - although, I am continually amazed (I have stay there a few times) a the number of Miracle Mile shoppers I see staying at the hotel.
The hotel is worth a stay (is that even a phrase?) whenever you have business in the downtown Chicago area. You will have easy access to any of the major transportation mechanisms and a convenient walk to decent restaurants - and, if you are interested, world-class shopping (and people watching).
The hotel also offers easy access to runs along the lake. A huge plus in my opinion!