Hey Matt, I understand you don't want to share the internal node structure of the easy clouds, which is understandable. But perhaps you can give us a hint on how you keep the clouds so tight, with detail?
The Altocumulus Castellanus clouds can get some very tight Cumulus like forms which are hard to do with just Perlin Billows or Voronoi Billows without having too much stray "blobs". And when you mask by smoother forms, trying to clamp in the forms, the look just isn't right.
What's the secret?