How about an invigorating snowshoe trek with an experienced naturalist to guide you? For a family adventure (kids of all ages welcome) drive up to the Mazama Ranch House and meet up at the yurt for a free snowshoe tour.
Snowshoe rentals are available as well, and hot chocolate awaits you at the end!
If you prefer to head out on your own, the MVSTA, Sun Mountain Lodge, and the Loup Loup Ski Area all have excellent areas for snowshoeing.
Be aware that you are sharing the woods with many animals, both large and small. Please follow safety precautions.