One area where a bit of creativity can come in is to create black-&-white images from colour ones using the RGB channels selectively. It is the same as using colour filters with B-&-W film, but can be done later.
The first two images here are the same frame, the third made half a minute later; the tones vary using this method.
The final one was taken on another day at the same place, and although conditions were different it shows, I think, how radically an image can alter using this technique.
There is so much that can be done to change the look of a B&W. I often convert just to see what extra I can squeeze out of a shot and to see if I can get anything stronger over the original color version.
I personally prefer the 2nd. It feels it has greater depth that the first - I feel my eye is drawn from the foreground through to the contrasting sky.
#4 just doesn't work for me as I seem to bounce between foreground and sky.
#3 is broody as you suggest, just a bit flatter that #2. It does though accurately covey a grey and miserable day........
I'm not really sold on any of these myself, Alan, but groping for something I've yet to attain. Some simple, "essence" type of image. I want to keep it simple, and not necessarily "photo-realistic". No. 4 is certainly taking things further. I enjoyed playing around, and thought I'd share for illustration mainly.