I personally like Render_Test_2

Very cool clouds on that scene.
The other scene is also cool too but seems dark looking and looks like a really dready bad day for mountain climbing.
Here is an idea, if you could add some effects of a rainbow in there, somewhere where the sun is shining though the
clouds it just might brighten the viewers eyes to the beauty of the scene.
A few years ago I made a quick tutorial how to create a realistic looking rainbow using Phtoshop for
some Aviation art fans, and if your interested I could always send it your way if you want to do some post-work
special effects with this image using Photoshop. Just an idea.
But I defenitly like the Render-Test-2. Came out real good to my eyes.
Congrats!