For an image like this Nick, it makes it easy to duplicate the image, treat the sky and foreground differently in each copy, then combine them back into a single image. That part can be done without layers but it is so much easier with them.
Where layers really come into use is when you need to merge elements of more than one image into a single image as in combining a focus stack, bracketed exposures, or replacing a dull sky with a more appealing version.
Take a look at the Project 52 link in my signature for numerous examples with the steps involved to achieve the results.
Looks like layers can help with some really common problems.
Maybe I can look into a plug-in.
Thanks
Now the image looks great Ernie It would be a pity not to see this foreground with nice colours and details. I would crop about half of the sky.