Here is my interpretation of your landscape scene with the processing steps I took. As with anything like this, each individual has their own vision/idea of how the scene should look.
I opened the file in Camera RAW two times.
I used two different settings and opened one image for the shadows pretty much as is and opened one image to open up the shadows a bit.
The Camera RAW settings are shown here:
I took the lighter image and copied it onto the darker image.
I set the lighter layer at 50% opacity in the layer pallette.
I duplicated the lighter layer.
I added layer masks as shown in the final attachment. The upper layer was masked a bit darker than the lower. This was done to keep the sun in the valley the same as the original darker image yet raise the shadow area up and fill in some detail.
I finally added a hue/saturation adjustment layer with the saturation at 20%.
Whoops! I just noticed the layer masks were not visible in the screen capture so I made a new one and added it here:
I can provide the full Photoshop file for you if you wish to see the full image.