I am a terrible decider. So I am leaving it (mostly) up to you.
Honestly, I am just unsure as to where to go now that the basic planets are finished. I do plan on doing the Sun and Moon at some point...but those aren't really planets. (Those will probably be done regardless of what you vote...sorry if you hated the whole series.)
And if I left out a completely brilliant idea, let me know in the comments...just remember I am not super skilled. No Sistine Chapels please.