You could spend a month in Kyoto and not see all the sights! Of course, there is also Tokyo if you want to see the hustle-and bustle. Don't miss the suburb of Tokyo called Akihabara electronics town (block after block of electronics shops).
And any Honda fan should be ashamed if they miss out on a visit to Honda's Twin Ring Motegi race facility and the Honda Fan Fun center and Honda Collection Hall historical museum. It is just a few hours north of Tokyo. Here's the web address for more info:
http://www.twinring.jp/english/information/index.html