Petrified Forest National Park, we passed the Zuni Pueblo, and reached a forest of Ponderosa pines.
Junction Cave is several hundred feet long and is easily accessed at the end of a short trail off the main highway. If you intend to visit, be sure to get a free permit from the visitor center. The cave is bat habitat, and the park is extremely worried (with good reason) that the white-nose fungus might attack the bats. The fungus has decimated bat populations back east, and has been moving west over the last few years.
Lava tubes are not "decorated" in the manner of limestone caverns, as solution (the origin of stalactites and the like) is not a prominent process in the volcanic rocks. On the other hand, there are occasionally flow structures and drip structures ("lavacicles") that can be seen. Some of the caves may even preserve ice masses long after winter has ended (there is a commercial ice cave at the park boundary).