Great photos! Especially 1 and 4 (my taste, all have the colors, but 1st also have structures I like). Need to go there some time, recently was a program on Swedish public service TV (american production bought in), though they focused on super-vulcanos, there were fantastic views of Yellowstone. Hope I get a chance to see it before the super-eruption
I noticed it is really useful when using polarization filters for landscape to shoot both at maximum filtration effect and then turn the filter 90 degrees and take a second shot to learn how much effect it has.