Sorry that I misread your post.

A few references for the ryokan Kagaya at Wakura onsen (post #24, #31) where we stayed.

http://www.flyertalk.com/forum/showt...=682072&page=2

The Kenrokuen garden in Kanazawa is famous for snow scenes.

The other famous garden Kairakoen is in Mito. It is the place to do ume hanami (plum blossom) so mid to late Feb will be best. You can enjoy ume everything (plum soba, plum wine etc) and nato (fermented soybeans) everything too.

The Sapporo Festival mention by Marq above is a good idea too. It will be next on my list.