I've been staying at this locations several times a year since I was a child. It goes without saying that I'm a fan. I've never had any major issues, and any minor issues are handled quickly and
above my expectations.
I personally recommend the executive tower over the historic tower, the rooms in the historic tower are a good bit smaller (especially the bathrooms), and after a long day in the city you'll appreciate the extra space you get in the executive tower.
I only have two minor things that I wish they would "change". First, parking is WAY overpriced. I get it, you're paying for valet in a big city at an upscale hotel, but $60 (or $50, if you prepay) a night for parking is much too high. I suggest using one of several parking apps/sites available for Chicago (ParkWhiz and Parking Panda are my two favorites), I regularly pay half of the hotels rates or less, usually less than 4 or 5 blocks away from the hotel. Secondly, I really wish they had an executive level and lounge... it's splitting hair, I know, but it's a really nice thing to have that I've been missing at this location. [Less]