As for future suggestions, I think sky colours will go a long way. You do have sky colours but they are not selected by default and are particular to certain areas, weather situations and time of day. I'm not saying you should get rid of these textures, just add some all round nice sky colours that work all around the world.
Another suggestion is different coloured clouds. I know you have this implemented but it is like tile load (all clouds in the same tile load are the same colour). Maybe we could have different colours in the same tile? Good transitions?
But definitely, I'd say these should be in v4.