We did a snow coach tour to Old Faithful from West Yellowstone, then did two half-days driving the Lamar Valley. The highlight, as it often is, was the bighorn sheep on a hillside near Soda Butte. There were two rams, one older with a full curl and one younger with a smaller curl. The hillside/cliff they were navigating looked very steep and I got some shots of them climbing around. Click here for more images.
During the snow coach tour the first day, it was snowing constantly and the wildlife was limited to bison. At Old Faithful, the estimated time of eruption came and went. It finally went off 47 minutes after the estimate, which our driver said was the latest he had ever seen in 20 years. The best shot I got of that is a video, below.