Haha, that is very relevant to me. I have started on a concept like that many times, but stopped very quickly without knowing where to go.
Most recently, I've started a 2d Elite-inspired idea. I'm still working on procedurally generating the galaxy.
This idea sounds very similar to Starbound as well! If you haven't, check that out. The problem with it for me was that after awhile each new planet felt the same and it lost it's appeal quite quickly.