I love to create Channel Masks to get a selection if the image allows.
This image is perfect for that.
There is a natual mask within the image itself.
In the Channels Palette, click on the Red, Green, and Blue Channels
to determine the Channel with the highest contrast. Here, it is the Blue Channel.
Duplicate the Channel and run Levels to darken the dark areas (shadows) and
brighten the light areas (highlights).
Don't over do it.
Finish the mask off with the Dodge and Burn Tool set at a low opacity (10%).
Duplicate the Background Layer and load the mask as marching ants.
Change the blending mode of this layer to Multiply. Apply a Layer Mask. If the foreground darkens instead of the sky...oops, invert the mask.
Finish off the image with a nice "S" curve in a Curves Adjustment Layer
and some Paint With Light (PWL).
Flatten.
If still not vivid enough, increase Hue/Sat or use Selective Color to boost specific colors.