My idea: A large planet, maybe 1.5 times the size of Kerbin, with very large gravity. The surface has no atmosphere, but the planet is also criss-crossed with valleys, and inside those valleys there is a thick-ish atmosphere (maybe with oxygen, so jet engines can be used). Landing outside of those valleys would be extremely hard, kinda like Tylo, but players can also use parachutes to land in the valleys. I think that would be a very interesting planet to go to and land on :] (I do realize there's another thread relating to new planets, but that thread just confused me.)
