Your buildings are a lot prettier than mine. I've only put any amount of thought into a single building, a massive storage warehouse that has automatically sorted containers for just about every item in the game (only excluding project parts and radioactive stuff).
All of my factories in the starting area feed into one of a few highways that go back into the sorter, then excess stuff gets chucked in the sink.
I'm in phase 3 and the last big milestone was unlocking trains, so I've started exploring further out and building train stations then putting down rails on the way back. I'm about halfway though building a handful of factory outposts for different parts of the space elevator. It's a lot of fun, but tbh I'm kind of dreading the next couple of phases because it's already on the verge of being overwhelming. I saw on the mods page someone uploaded a save with a full rail network connecting the entire game world, if I ever start over I might give that a go and have a huge moving base. Probably won't be practical, but I'm enjoying the hell out of the train stuff so far.