I stayed at the Century Hyatt last year right after Christmas. It's next to Tokyo's futuristic looking city hall. I liked this Hyatt although I would have preferred to stay at the more upscale Park Hyatt, but I couldn't get an award room there. The staff at the Century Hyatt was tripping over themselves to be helpful. There are plenty of office buildings with top floors full of restaurants right across the street. There are even 2 Sizzler restaurants if you miss that type of food. The hotel has a shuttle to the Shinjuku station which is under a big department store.
I was pleased with the size of my room which seemed to bigger than many of the ones I've seen in Tokyo or Hong Kong. My rooms was also bright, clean and very well kept. I thought that the big brass key was a kick.