Family trip mid December: where to?

Hello,

I am trying to take my daughter who is 4 years old on a trip outside Tokyo/Yokohama during near Christmas time. I was thinking more southern Japan. (Except Okinawa). Does anyone have a good place they can recommend for a child at that age and it may not be as cold?

Please no Osaka or that area either.

Thank you,

by throwaway_acc0192