froyd, these shots were taken yesterday, around midday, at a local beauty spot. Though a bright and sunny day there was a lot of cloud. These were jpeg shots, accidentally I might add as I always shoot RAW. I'd been playing with settings, like you do, and forgotten to put it back to RAW.
The highlights in the clouds had blown right out. I prefer B&W anyway so changed it with LR4. I find the jpegs from the camera can't stand much post processing but in answer to your question I did indeed darken the sky, not by much, but I am guilty🙂
Paul