ol' faithful is awesome, but exploring the rest of the geisers there is definitely worth it. When I was there a few years ago some huge geiser went off that had only busted it's load once before in the last 15 years
Looks like someone has only seen Yellowstone from the road.
Too bad most of the good trailheads are covered in snow : (. There is straight up 5 feet of snow on the Ashton-Flagg Ranch Road. Bechler Meadows is completely inundated with water and pretty much every river is too high to cross. Your options are really limited this time of year. Right now is a great time to photograph wildlife though, just this last week I got lucky and nabbed some shots of a grizzly and sandhill cranes.
If i remember correctly you can mountain bike a really dope long trail but i am not sure if it Yellow stone or not its one of the parks near where i live