I use the "ULTRA" settings in Terragen. Like Vue, the higher the settings, the better your renders will look. Also note, I'm using the 3D setting (2D works for a lot of regular Terragen renders- but 3D is BEST if you are a real CLOUD FANATIC). One other thing is make your sky HUGE! Like 10000 or 20000. Of course all these things increase render time- but you can use your beautifully rendered high-rez Terragen Clouds in Vue OVER and OVER, many times, so its a good investment of render time...