A superb location and a file with more potential than is being shown (web version or not).
Try bringing up the detail in the shadows. I realize this is backlit, but to have the tree and cliff foliage near black turns it into an unnecessary black hole.
Also, try brightening the light coming through the arch to accentuate that feature. There is some beautiful golden light there.
Please don't take offence to my changes shown below. I don't presume to know what you were trying to do, but here is another take on the same scene that may offer some ideas. The settings are included; the shift in Hue was applied to the blue of the sky in the top right. I also used the Adjustment Brush to brighten the trees through the arch by +0.2 Exposure and +10 in Colour Temp. There is still more that could be done, but this is a start, anyway.