I stayed here for a week while in town visiting family and friends. I've stayed at 5 of the 8 Peninsula locations and although this is certainly one of the more luxurious properties they have, the service lags behind the other locations.
Now by no means is the service "bad;" just not up to par with it's sister hotels.
At the other Peninsula locations, I would consider the service (relative to other hotels, not just the Peninsula Chicago) above and beyond; over-the-top; and sublime. At the Peninsula Chicago, I would consider the service as above average.
For instance, at other Peninsula locations, they welcome you with a welcome drink in the room and possibly a light snack. No such greeting at the Chicago Peninsula.
At other Peninsula locations, when the Spa was booked, the receptionist offered to either call me if there were any cancellations and even recommended some local Spas - not at the Peninsula Chicago.
The rooms are great, the location couldn't be better and the restaurants are top-notch. My friends that live in the neighborhood all love The Bar at the Peninsula as well as the Chocolate Bar they have every Friday and Saturday.
It's a wonderful hotel... the service just isn't over-the-top as I've come to expect having stayed at most of their other properties.
The hotel accommodations are important but not as much as customer service. At the 5-star level one expects a high level of customer service. The Peninsula Chicago's customer service is attentive at best, mildly impersonal at worst.
The Park Hyatt next door isn't quite as luxurious (a little too contemporary for my taste) however their service was surprisingly helpful. If location and a high level of customer service is all you desire, you may want to look into the Park Hyatt Chicago; for shorter trips, I know I will.