Firstly.
Do it yourself.
Then talk about it.
Do not make suggestions that have been suggested a billion times before. We have seen them, we have read them, we have replied to them. Every time the person says that they could help out the modders in the work.
Well bloody do it. Don't just say you will, DO IT.
Secondly, this idea can easily work.
You would not do it for every planet, maybe only one or two.
Very simple method would be this.
Floor, made of different chunks (Gameplay mechanics, there's a visual distance to see things remember, if the centre of the floor is too far from the player, you will not see it), with hills etc and the biodome trees used.
A small citylike structure, these can be achieved with low poly counts.
Nebula for clouds.
A station orbiting just above the 'clouds'. You dock with it to leave.
