Far-look and fog are not satisfied.
My foggy grainy, may I ask what is the reason?
Pretty! I like your fog, but my eyes may be tired. Little sunrays so nice. :) Is that a local cloud or atmosphere? I am having more luck turning voxels off, but that is probably a bad answer.
Most probably the atmo samples needs to go higher. Double or more the samples you have now.
The quality of the cloud can also cause similar effect. Try to increase a bit also that but do not go above 1.0. It will slow down the render very much.
I have never paid any attention to the "voxels" parameter and need to research it. I will also raise the sample to find a balanced value.
This is lovely, I especially like the sunset one. As a minor suggestion work on the far background, trees and small hills off in the far distance. I think it would really pul the scene together.