I rather like the first shot, despite the colour 'popping' not being to my taste.
how do desaturate different parts of the photo by different amounts on photoshop?
*cough* lightroom *cough*
Try the 30 day free trial. You can actually 'paint on' different degrees of saturation/desaturation/just about any characteristic.
I can't recommend it highly enough, in fact, for this sort of photographic work.
I'd second the comment about squeezing a bit more contrast out of the sky, but again that's a 30 second job in Lightroom with a custom gradient, which you could slso use to desaturate…
Oh, just give it a go. I *promise* you'll love it and, if you don't, I'll send you some VW sausages in the post.