As Gary indicated, wallpaper is really about a photos that you enjoy viewing again and again. Although I have found a very few over the years that did a fine job of hiding the icons on my desktop! (Good for reducing clutter, but hard for working…) 
This is a view across the Porcelain Basin on a day where the sun was shining as I started wandering around Norris, but heavy clouds had moved in by the time I took this shot. The heavy clouds did a fine job of showing off the different colors in the hot springs. (5D3, 24-105 @ 29 mm, 1/125 s, f/16, iso 200, tripod)
There is a lot going on, but your comp pulls it together rather well. I really like the colors and the steamy and dramatic mood. I can see why it is a favorite.
Being able to see through the water on the closest pool is such a great plus in this image, I think. And the arrangement of the pools make them look like a big meandering river of some sort that draws in the eyes into the image. Gorgeous clouds, too, Mark!
I really like the colors and the clarity of the pools Mark. For me, the steam, along with the clouds, add just a bit of mystery to the whole image. Very nicely done.
I love the gradation of greens and blues up the frame, interspersed with the warm toned soil. And the detail in the foreground pool is very cool. I can see why you like to revisit this often.
Lovely flowing textures and delicate hues with no particular focal point seems ideal for a wallpaper, Mark. A very appealing shot.
Mark: The light really makes this shot special. Getting some detail in the clouds is a really nice plus as well. I’ve never really explored the Norris area in any detail so I’m going to have to put it up higher on the list for another visit. Marvelous image. >=))>
This is a fascinating and expansive landscape, Mark! The greenish, transparent pool with the clearly visible formations got my attention immediately as it has a kind of other-worldly appearance. Then, as Adhika stated, the water seems to wrap around and carry you further into the scene where there is lots more to look at. The steam everywhere adds a lot of interest also and the broad expanse of the scene is also impressive, especially when viewed large. I can see whey it would one of your favorite wallpapers!