For me, it has to be the mix of the sky...white clouds, blue skies, and a bit of yellow (or orange):

For me, it's about as peaceful and calming as can be...I kid you not, I used to always look to the skies for UFOs or whatnot, but now I'm content with clouds and the sun playing off one another. Who needs high strangeness when there is just nature? Plus, Hattie loves my pics and loves blue, so it's a win - win, lol!