Thanks to everyone for the feedback.

To answer the question about why I limited myself to these two properties, the simple answer is price. I was able to get fabulous rates at both. I finally decided in favor of the Park Hyatt. Since I had a hard time making a decision simply based on location, I considered some additional factors.

One thing that had concerned me about the rate I got for the Nikko is that I got it prepaid, albeit deeply discounted and fully refundable, from Expedia. The rate I got for the Park Hyatt was direct with the hotel. For some reason, the Nikko would not match the Expedia rate when I inquired about booking directly with them. Last week I tried calling Expedia to ask some basic questions about what was included in the rate and they couldn't answer. They said they would contact the hotel, put me on hold and about a half hour later came back on the line and said they couldn't get in touch with anyone at the hotel who could speak English to them. Based on that experience, I'd much rather deal directly with the hotel if I encounter a problem than having to work through Expedia's customer service.

This leads me to the second factor I considered, which was the level of responsiveness of the hotels to my inquiries. I emailed both properties late last week with some questions. The Park Hyatt responded to me within three hours. Hotel Nikko on the other hand, has still not replied almost a week later. That makes me think there may be something to what Expedia said about not being able to reach English speaking staff to talk to.