Country Inn Milky is a wonderful peaceful family-owned place, great value for your money if you stay in Niseko. The owner speaks pretty fluent English (better than staff of many hotels!) and breakfast is great (though they didn't tell me in advance that it requires additional payment, neither have asked me whether I even wanted this, which kind of disturbs me, though I would have opted for it anyway).
The rooms are big and the beds are very comfortable. They are perfect for families. There's free WiFi in the common area but not in the rooms (I was actually able to catch low signal in my room with my laptop but not the phone).
Niseko ski resorts are very close (note that I rented a car so I don't know about public transportation). I should warn you though that aside from the ski resorts there's nothing much to do in Niseko in general so if you're not into skiing you should reconsider whether you even want to visit the area.