My wife and I made our first visit to Yellowstone National Park in March 2006, shortly before the end of the winter season there. We rode the Bombardier B12 snowcat from West Yellowstone into the Old Faithful Lodge for a couple nights. The snowcoach made stop along the way so we could admire the wildlife and the scenery (the vertical shot of the trees in the snow in the Yellowstone Gallery on this site was made on one such stop, by standing up through the open hatch on top of the snowcoach).
The temperatures were as low as -23F during our stay, but we enjoyed going out with our cameras in the mornings. We have since made two more visits to Yellowstone and have become loyal enthusiasts.