鬼怒川 (Kinugawa) is very close from 日光 (Nikko). It is not as touristic but, I feel, it is more enjoyable, especially in autumn when the leaves turn gold and crimson. I organised my second trip there with a few good friends: Alexander, Christian, 亮助 (Ryosuke), and Kathy. We spent the night in a 旅館 (ryokan) in which we had very good food and a revigorating sleep.
If you want more information about the area, please check the guide page for 日光 (Nikko).