I struggled with that in my mind as well. The horizon actually does bow down towards the San Juan in that direction, which is what I was struggling with. Even so, you're right. Could probably stand to go counter-clockwise a degree or two, judging by those plateaus on the left of the horizon, which should probably be pretty parallel with the top of the frame. Thanks for your thoughts, anon.
The colors can be pretty vivid to begin with. In some cases I tone them down or shift them towards a more accurate color. I shoot in RAW, so the contrast straight out of the camera isn't all that impressive (that's what Curves is for). A RAW file has been compared to a film negative by some, but in addition allows you to compensate for white balance and slight exposure errors. It allows you a bit more creative freedom and edit ability than your standard JPEG.
Well, of course, the image is fine. It's just that with some images, I get these David Muench moments where I envision for example, here that the flowering bush IS the foreground rather than simply being in the foreground.