Kusatsu or Minakami onsen ?

We have only 1 night to spare in between skiing in Yuzawa (in Feb) and driving to Nikko along the romantic road (route 120 from Numata IC). As a tourist, Kusatsu is a famous onsen town but we also just heard that Tanigawadake has some wonderful onsens so maybe someone can advise on choosing between the two areas. Of course Tanigawadake is more convenient but IF Kusatsu is a lot better then we are prepared to make the detour.
Also would appreciate advice on which hotel or ryokan to stay for around yen 20,000 to 25,000 per adult per night with 2 meals. Mainly looking for good food and a nice rotenburo. Many thanks.

Kusatsu has the best onsen water that I have yet experienced. I also love the town with its yubatake. In Tanigawa Onsen is one of the best onsen ryokan I have yet stayed at (Senjuan), but it is slightly above your budget.

Another onsen to consider is Hoshi Onsen, especially if you like old fashioned wooden indoor baths (no rotemburo):
http://www.japaneseguesthouses.com/db/gunma/chojukan.htm

There is a very nice traditional inn called 'Naraya' in Kusatsu, which offers you a reserved opne-air bath. They will charge you between 17,000 to 34,000yen. Please check www.kusatsu-naraya.co.jp

If anyone else knows of any other ryokans with good food and nice rotenburo between Yuzawa and Numata within our budget, do let me know please.

Another popular one with rotemburo (mixed gender) is Osenkaku Ryokan in Takaragawa Onsen in Miankami:
http://www.japaneseguesthouses.com/db/gunma/osenkaku.htm