Get Geto on a peak day and you can't get much better. It's renowned not just in the region but in Japan (I believe) for excessive amounts of snowfall and 40-50cm+ regularly is not uncommon. There are some good official tree runs as well which are worth exploring if you are competent enough. Not the most accessible ski resort but worth a visit if it is within reach.
Not sure what it would be like for families and stuff, but for