Chicago's Magnificent Marriott!
If you like to be in the middle of everything, then this Marriott's for you! Ideally located on Chicago's Magnificent Mile, this hotel is just steps from it all: Shopping? The Shops of North Bridge (anchored by Nordstrom) are a few steps South, and of course, blocks of retail shops spread out to the north, all comfortably within walking distance. Interested in an Architectural Canal Cruise? The Wendella and Shoreline boats are a few hundred yards away. Millennium Park, Grant Park and the Art Institute are just a stroll to the south on Michigan Ave. And if you're in town for a Cubs game, catch the "L" train at Grand and State, just a few blocks away. You'll save a ton on cab fare by walking to all the places you'll want to see!
Because of its location, this hotel is in high demand for meetings. In fact, everytime I've been there, at least one conference was going on. (I'm planning a meeting there, myself, booked for September.) You'll see the effect in the crowded atrium bar ("Rush") in the evening and in the concierge lounge in the morning. They're usually packed, as is the Starbucks in the lobby. 
During my last two trips to this hotel (both in July '12), I was fortunate enough to stay in a suite (the same suite, both times, actually! 4511). The bedroom is an average size; but the bed is exceedingly comfortable. Plenty of electrical outlets in both the bedroom and the bathroom. The suite is huge and is comprised of a seating area, Murphy bed, bar area with bar sink and fridge, and another full bath and closet. Both were tastefully decorated, and while clearly not "new," they were in good condition.
Now for the bad news: WiFi is expensive at $14/day, if you aren't a Platinum member (they get it for free). Valet parking is $51/day; and high-$30's for self-parking. The Concierge Lounge has a great breakfast, but you'll have to fight for a table. But if you're prepared to pay, you'll truly appreciate the convenience of this location.
Final verdict: STAY! Give it a try. If you're like me, you'll return again and again to this hotel to enjoy the Magnificence of Chicago! 
Wishing you safe travels!