Before we went to Japan, we looked in the Internet for more information about what to expect. Some of those sites are rather interesting.
E.g. this site shows a skyline view in Tokyo of both the current and optimal conditions:
(Make sure to press "English Home")
And the current weather conditions can be found at:
Infoseek weather report for Tokyo
Yahoo Weather report for Tokyo
Public transport is excellent here. For those people living in SF, let Muni come over here and take a look. Only once have I had to wait a long time for a train, and that was because of a suicide. Usually one train leaves the platform and not a minute later the next one arrives. There is a vast network of subways, trains, and busses. The only shortcoming is they haven't heard of a night train or bus. You can only take taxis between 12:30am and 5:00 am.