That said, all this research and thinking about visual style ended up shooing me back to the planet renderer again. I kind of came to the conclusion that I'm aiming way too high here. I can wrestle with GLSL and get normal mapping and all the rest of that crap in there, but as just one guy it's not like I could ever create visual fidelity to match, say, Eve Online's attractive planets. All I could do is fall short. Perhaps I need to back off and think different. It's not like the goal is just fancy graphics, after all; it's a big space exploration game. Perhaps I need a new visual style.
What if there wasn't a graphics card arms race that had been going on for two decades, and instead you were playing the game on an Amiga 500 with four gigabytes of RAM? Simple graphics and deep gameplay and story. That's the direction I should start thinking in.