Thanks all for the info, I was just reading a stack of info on the main snowjapan site, and Hakuba/Nagano really looked appealing.
My mum has mentioned she'd be interested in trying cross country skiing
My bro and I will hit the slopes
My dad is not that interested in skiing, so he could explore the castles, etc.
Plus it appears there's many onsen in the area which should be good.
Not to mention a huge variety of cabins/lodges, so I'm thinking I'll be in Nagano with my family for new years eve! We might stay 3 nights.
Now I've just got to figure out transport etc