Hi Tony,
You're welcome. My apologies too - I almost missed your reply (the latest threads page seems to scroll by so fast these days!)
It was a combination effort in ACR and Photoshop - I was hoping to get by in ACR alone (often can) (that's why I wanted the RW file with all information intact). In ACR I'm really just pushing things as hard as I can whilst moving it towards how I think it should look - I'm afraid that that part just comes down to experience (seeing what an image needs from a technical perspective, and then knowing what combination of controls gets it there). I STILL couldn't get the sky where I wanted it though - so I pushed it through ACR with more noise than I wanted, and then processed it seperately as a selection in Photoshop (with some noise reduction).
I also used LAB mode to bring out the colours in the rocks so I could push the magenta/green axis without touching the blue/yellow axis (which would affect the sky) (a straight saturation control would not have driven the colours apart and would have messed up the sky).