I have stayed in the Park Hyatt, the Grand Hyatt, and the Westin Tokyo in the past 3 years and have found the P-Hyatt to be one of the best Hyatt hotels I have EVER stayed at in my life. The service, the rooms, the amenities are all the worth the money, IMHO.
Most of the meetings that I had in Japan were actually held at the hotel so I didn't have to travel far to get to where I wanted to go to. I enjoyed the shopping, the food, and all there is to see in Japan. BUT those of you who are use to steak and potatoes will be in for a shock when they go to Japan.