I've been playing creating a planet with out using the planetary shader (cos it's cheating
). With the fractal terrain I found to get decent continents you need to set the Feature scale really big e.g 5000000. You've got to remember a default planet has a radius of 6378000, so 5000000 is less than a eighth of its circumference (2 * PI * radius) .
I've still got to figure how to do water properly. I'm cheating at the moment and using a second planet with overlapping the first :-) I ought to try a conditional shader based on the sea level