Edo Wonderland Nikko Edomura is a historical theme park built around the streets, houses, theatres, and costumes of Japan's Edo period. The setting is theatrical rather than scholarly, but it is well done: samurai residences, rural lodgings, ninja shows, traditional performances, and costumed staff make it easy for families to spend several hours here.
It sits outside central Nikkō, so plan it as a separate half-day rather than an add-on to the shrine area.