We spent 3 nights/4 days camping and snowshoe hiking with Yellowstone Expeditions.
We stayed in heated tents and were fed and guided on snowshoe hikes each day. In the afternoons we did wildlife viewing in the Hayden Valley. The wildlife was great. It was also really fun to have that whole section of the park to ourselves once all the snowmobilers went home for the night. Great experience, one I would do again.