Tokyo Getaway - Suggestions ?

Hey there.
I just landed in Tokyo and going to spend here a week for business. Since it's been a while from the last time I was in Japan, I took a week off and decided to have a week of onsen, nice food and nature.

i'll be in Kusatsu Onsen 3 days doing hiking and just relaxing at the onsen but still missing a plan for the other 4 - Any suggestions ?

i'd be more than happy to hear about places that are not that far from Kusatsu or on the way back to tokyo (so I wont make a huge expensive loop or spend too much time and money on transportation)

I hope it makes some sense :)

thanks ,
Yonatan

Nearby Minakami has also some good hiking (and currently good autumn colors) and onsen:
http://www.japan-guide.com/e/e7460.html

If you are driving, you could return to Tokyo via Nikko, accessing Nikko from the back via Numata (it is not possible by public transportation):
http://www.japan-guide.com/e/e3800.html

Alternatively, you could drive from Kusatsu via Shiga Kogen to Shibu Onsen and see the bathing monkeys. It is possible by car until mid November, and by infrequent buses until November 4:
http://www.japan-guide.com/e/e6025.html

You know, if you're using public transport you could always buy a 4-day flexible JR East pass for 20000 yen (or 16000 if you're in the 12-25 age group), and head into Tohoku. There are so many beautiful places, and plenty of onsen. If you're already planning to ride the shinkansen, you're out of pocket over 10500 for the return trip between Naganohara-Kusatsuguchi Station and Tokyo. Depends how much you want to spend, of course :)
http://www.japan-guide.com/e/e2361_02.html
http://www.jreast.co.jp/e/eastpass/#category02