Hand written card from Guest Services asking for a 5* TA review!
Hyatt Regency Chicago is a huge hotel in a prime location, therefore we would never pay rack rate to stay there, and still wouldn't consider it for a moment even after receiving 5* service for our two night Thanksgiving stay. Considering what we paid for our room (via Priceline bid) we are very satisfied with our overall experience, however cannot give 5* for two reasons: 
1) There is ZERO sound proofing in between rooms (we were in #2810) - it is as if your fellow guests are hanging out in your room. Even the slightest noise could be heard - the clink of a key to the South, all the way up to full blown party to the North. Let's just say if we HAD paid regular price we would not have been too thrilled!
2) The bed was definitely plush, but 2 nights = 2 mornings with a very sore back. I think the mattress was just getting to the point of needing replacing, or it is simply not supportive enough in the first place. Of course that is a very subjective thing, and I wouldn't have knocked a star off for just this reason alone.
Apart from these two points, everything was very enjoyable. On check in I said the magic word for free wifi, and free wifi is what we got. I also asked for a room as high up as possible, and was happy to be offered the 30-something floor... but then the receptionist mentioned that the view wasn't great from that particular room - would we like a different option? So we ended up on the 28th floor overlooking the river with a restricted but still very fine view out over Navy Pier to the lake. Apparently this would have been an upgrade even for regular rate, so for $65 per night it was much appreciated! I love the city... from a bird's eye view!
So we decided to take a nap (rather full from Thanksgiving Buffet with family at a Hilton in the suburbs) right after checking in at around 6:30PM. A little while later we heard a knock, which was just discernible as being at our door over the partying that was going on in the room next to us - someone at which had already hammered once on the door 'dividing' our two rooms! I thought it was someone looking for next door, so I stumbled (in my sleeping 'attire') to the door and told the person that they were knocking on the wrong piece of wood. A lady's voice mumbled something, but I heard my name. I asked her to give me a minute, and then opened the door to find Guest Services with two bottles of water, a package of chocolate covered toffee, and a 'we love you, thanks for interacting with us on FB, here's some goodies, please leave feedback' hand written card! Baffling service to receive in such a vast hotel booked via a discount website - but what a way to roll! We were very impressed, and yeah I really wish I could give 5*. But if a hotel can't make at least an attempt at inter-room noise control then I don't see how they can expect 5* reviews. It's as simple as that. If there was the option, this would be a 4.5* review, but oh well.
Big Bar is wonderful. The Bistro was fine. Renovations to the other restaurant areas are ongoing, but there is still also the Irish Pub themed bar available. We enjoyed the food and drinks and received fantastic service all round. Yes, it is expensive, but not shockingly so.
There ya go! Pay your money, check in, and pray for quiet neighbors. Unless of course you plan to party yourselves - in which case PLEASE try and be considerate to those who are basically sharing your room with you.