Firstly, I'd like to commend you for your creativity. It's no fluke some of your screens ended up in the 'Legendary Terrains' thread that's for sure.
As for your first one, the best of the three as far as I'm concerned, some simple edits would suffice.
The waterfall would better off tinted to match the stream. As you mentioned, the fog is immune to colorchanged, however the waterfall is not.
The other matter bothering my eye is the railroad topping the first step of the staircase. It'd look better if the railroad ended a few squares earlier, perhaps by a blockade of some sort.
What makes the picture shine is how incredibly detailed it is.
Well done.
The second picture,not very much to my liking. Despite the fact that it is, as well as the first one, incredibly creative, it doesn't really look good.
I suppose what's mostly bothering me is the fog tint. It needs to be saturated, heavily. Pure blood red is 'no no' for me.
The third one could be similarly described as your second. Incredibly detailed and creative as can be, yet artistically lacking.
Only thing I can recommend here is that you use 'less effort' believe it or not.
Actually constructing the earth is going overboard, a custom model would tenfold the appeal.
However, I do suppose you enjoy doing this.
That concludes what I have to say on this matter. I do hope you stick around the terrain board more frequently, because your creativity is damn entertaining to behold :3