This one. Taken last July, before I got the K10D. Why? Because I took it, my older son is the photogenic cowboy in the photo, and right now in Colorado, if it ain't brown, it's covered in snow.
The high country of Colorado is my favorite place on this big blue marble of ours.
This is on the way to the ghost town of Ruby, up Lincoln Gulch, near Independence Pass, the highest highway pass in Colorado. This is about 11,000ft (~3,700m). The stream is tainted reddish brown from mine tailings further upstream a mile or so.