Just wondering if anyone has found a settings configuration that helps alleviate the "planes" of visibility that are rendered when at a high airport (ie SEQM). If visibility isn't full, the engine displays the fog/cloud in a way that is somewhat variable and spoils the effect.

It's definitely a limitation of the engine/sim, so am looking for anyone who might have tweaked it to a more preferable appearance?

I noticed that too at SEQM.  I'm all ears for suggestions, too.

You might run it by Hifi on their forum here at avsim.  

Sprite based clouds probably have something to do with it.  It's possible that you could mess with cloud resolution settings, but that may not help with the lines as it's still a 2D object trying to masquerade as a 3D object.  I think, anyway. 

There is a setting in the options menu of activesky which I think is called cloud offset.  You slide the bar and it will offset the clouds that much higher off ground level.  The clouds will then not correspond to the metar but they wont be on the ground either.