So regarding the atmosphere settings, check the Lighting tab and play with haze glow amount and power. Same for your cloud layers, this can make a dramatic difference. Obviously, sun elevation will make a difference on how a scene is lit, I really like lower values for softer and more dramatic light. One last thing, in the Render node, Effects tab, you can up the Contrast value and play with gamma correction.
I agree that some people have come up with atmosphere setups that are extremely realistic and clearly elevate their renders to another level. There are many parameters that can be manipulated and of course it depends on the particular scene what works best. I am discovering new things all the time and I have been at it for years...
I like your render here, no need to be shy about it!
Add some depth to your clouds maybe.