Nikko is a small town and the temple area is located in a wooded area about a 30-minute walk from the train station. I managed to visit Nikko on a day trip from Tokyo. About half of the trip is via the fast Shinkansen, and the other half is a much slower local train.
The most famous thing in Nikko is probably the wood carving of the "hear no evil, see no evil, speak no evil" monkies. That trope has its origins here.
I highly recommend visiting Nikkor for anyone with a few days in Tokyo.
