Genesis II was made for CBS, who turned it down in favor of the Planet of the Apes series, with the thinking that a network could have only one science fiction show on its schedule at a time.
Planet Earth was made for ABC, and it wasn't a sequel, rather, the next episode of the same premise, with a new male lead and a lighter tone.
Star Trek: The Motion Picture's script was written to be an episode of Genesis II. (and was in turn, stolen from an older episode of Star Trek! (Earth satellite comes back looking for its maker))
Andromeda uses two of the characters' names (Dylan Hunt and Harper Smythe)though it has little to do with the original concept. By using the names I suppose the producers could call it "Gene Roddenberry's Andromeda") I really wish they would have made a Genesis II series instead,
IMHO: I liked that Mariette Hartley was set up to be a recurring, love-interest/villain for Dylan. It could have been a good show, though I have to agree with the poster who said it probably would have only lasted one season. Still, 26 episodes would have been great to have.