With the exception of some billing issues and the fact that this hotel is notorious for overbooking, we had a lovely stay.
The hotel is huge. Two towers and about 2,000 rooms. We had approx. 40 people in our group and we were spread out amongst the two towers. There were people in our group I didn't see again until it was time to check-out .
We had a buffet-style breakfast in a lovely restaurant on the first floor of one of the towers, the food was excellent. The hotel staff was polite and knowledgeable.
We stayed in room 3131. The room was stunning, we could see Lake Michigan from the window in the hallway. The view in our room was of the courtyard area.

I recently stayed at the Hyatt with my 2 children age 6 and 10. We were upgraded to Club level access with Jr Suite. Our room was a great size. One King size bed with a couches and a side chair. We had 2 large flat screen tv's and a mini fridge. The only down fall was that we only had a shower (with the amount of walking we did a soak in a tub would have been nice)
The club level access was nice-free internet connection, a variety of newspapers, a nice continental breakfast and a nice evening reception. Many days we just had a large lunch and ate at the reception for dinner (veggie and dip, breads, cheese, hummus, fruit). All during the day they had nice cookies and later at night great pies and cheesecake.
We liked the location. It was very central to what we wanted to do. It is centrally located to the Pier, Grant/Millinium Park, and the Miracle Mile.

We arrrived at the hotel at 12 noon and tried to check in-our room wasn't ready but the hotel took care of our luggage and said they would call us when it was ready. (Not really necessary as we were off to the taste of Chicago). When we got back, our room was ready and our luggage brought up.

This is a large hotel but we enjoyed it alot. The club access (or the clubhouse as my kids called it) was nice, you could meet other travellers and gave a nice area to relax in.

We would definitely go back to the Hyatt

My husband & I live in Michigan and wanted a quick inexpensive get-away to Chicago. So I started with bidding on priceline for 4-star hotel room in the Grant park area for $60 per night. To my surprise, priceline accepted my bid at Hyatt Regency. The Hyatt has done a good job at keeping the hotel looking "modern" and there is plenty of dining options inside the HUGE complex. The room was clean & the bed was very comfortable. The bath room showed the age of the hotel the most - but it was clean too. I would have given a 5 overall rating, but they gave us a room on the 7th floor with a view of an office building. However considering we paid 1/2 rack price - we really can't complain. Oh yeah, the workout facility is amazing and it's in walking distance of all the hot spots.

The hotel was full, but not once did any of the staff appear to be too busy to assist our group with our requests. We attended a program about customer service; the Hyatt staff were great examples. For a business trip, the location, the conference rooms, restaurants, bar, etc. were great. Downsides were charge for internet service if accessed from your room, high parking costs, and no pool.