These are quick and more fleshed out environments done with 3D-Coat, Keyshot, and Photoshop.
You've been busy! Cool seeing some classic sci-fi imagery here.
These are really cool! I would like to see a clay version to figure out where you used geometry and where you did the post work in PS.
These were some early explorations done before I found what I wanted to do with the environments. The rest was changing the background, adding some effects, and changing the mood. I try keeping them under the 4 hr mark (except the very top image).