As we see Kerbin has a detailed terrain with mountains and oceans but it would be great if it had rivers and mountains on Antartica because down to the poles it is so flat and not fun. Also more biomes on kerbin
Also on Duna it will be good if we added more Detailed terrain like Mountains, gaps on mountains where we can go through using our skills, Ravines and many more. Different colors on duna like on some biomes dark orange on some biomes light orange.