Emmaline, Elliot and I took a quick trip up to Yellowstone last weekend. It's only a five hour drive - you could easily include it as part of your UT trip...
Yellowstone is basically a big volcano. Over 2/3 of all geysers in the world are there. Elliot had some concern that the volcano was gonna blow while we were there but fortunately that didn't happen. We did get a picture of him in front of a geyser spewing 200+ degree water - hotter than boiling water because of the pressure.
Photos of some highlights below.... we saw a momma grizzly (no, not Sarah Palin) and two cubs but unfortunately didn't get a photo of that...