Thank you Mepher and Mommabird. 
THM, you're spot on in most of what you say, apart from the "heavy processing" bit. #3 was heavily processed, simply because it was taken on such a perfect day - clear, blue skies, lush, green vegitation, etc. - that it just didn't look right for Dracula's castle. I spent ages on that one.
#1 was a problem because of the low cloud base. There are big rock faces and snow-capped mountains right behind it, but can't see a thing. The main problem is that everything closer (to the camera) was much cleared, such as the trees you mention near, right, which almost made them look over-saturated, (I was wondering if somebody would suggest that). The focus was not on these but it does appear to be due to their clarity with less fog. Apart from some minor lightening of shadows and level adjustment, virtually nothing has been done to this... as I couldn't think how I could improve it. And I seriously think it needs some processing...
#3 was a problem because of all the blue - sky, lake and snow - which made it all look a bit weird, so much so that I put a warming filter on it and reduced the blue a bit. In doing so, it has lost it's 'icy-cold' look but I think it's better... but not sure
There was also a problem with the snow-covered trees, especially the ones in shadow, looking as if they had been over-sharpened, which they weren't; nothing was sharpened. It was taken in the early afternoon, and would almost certainly have looked better during 'golden hour' but never had time to hang around, unfortunately. I could also have done with a tripod!
The 'blood red sky' is an idea I'll look at, but I still think it needs something... Appreciate the comments THM, thanks.
EL_PIC, thanks for the comments but, please excuse my ignorance here, I'm not really sure what you mean. Can you elaborate a bit please?
60d, 400d, 100-400mm f/4.5-5.6, 24-105mm f/4, 50mm f/1.4, 580ex II, 2 X 430ex II, Bowens 500, cs5