Spending a night between Hakuba and Tokyo?

Hello,
we will be in Hakuba end of March and are planning to Travel from Hakuba to Tokyo by train. Any interesting places in between Hakuba and Tokyo were it would be interesting to stay a night?

Thanks for your help!

What are you interested in?

If you are also interested in onsen like I am, then I recommend to make a small detour to stay at Kusatsu or Manza Onsen, two onsen towns with some of the best water in all of Japan:
https://www.japan-guide.com/e/e7400.html
https://www.japan-guide.com/e/e7495.html

If you are into shopping and trendy restaurants, then I recommend Karuizawa:
https://www.japan-guide.com/e/e6030.html

The Fuji Five Lake area to the north of Mount Fuji can be along the way:
https://www.japan-guide.com/e/e6900.html