I've found that darkening in skies with nice cloud detail, a number 12 or maybe 15 filter is quite sufficient. A number 8 with a cp is good, also. A number 8 will not pose a big problem with greens in the shadows, and even a 12 shouldn't be to bad. Yellows to reds are even less a problem with the 8 to 15 filter range. The blue and parts of the scene lit by blue sky will darken.
Another thing is to underexpose slightly, and increase development the appropriate amount, which can improve the range of values in the scene.
The best things are exposure controls, including filters, followed by development controls, the last thing should be printing controls. Resorting to printing controls first seems, at least to me, to be putting the cart before the horse.