To be honest, I've been banging my head with clouds, which is fortunate I'm not having problems with walls. I agree with you guys that it should be brighter, but the exr conversion in photoshop popped up with this, which looked quite dynamic.
I have a method of building clouds from the base up, I also have a method of adding spherical billows, rather than lumpy billows, but when I try to combine these techniques I get somewhat thwarted by how TG wants me to work with texture space and real space. So this image was a journey into using the localised clouds to build a quick and dirty way of getting a shape I'm after, which as is, isn't it. The main structure is made with two side by side localised clouds, and a third for the base. Then there are two for the cirrus, and another for the lower spread.
I still have a lot to learn in deciphering the cloud node tab in terms of lighting, as I've spent most of my R&D time in the structure.