Goodeffort I would say. So, howto get things better... I would alter the mountain line, they frame the plain in apretty obvious rectangular way. Also some haze would help to get that sense of distance. Blending textures between plane and mountains and having the mountains rise not soabruptly wouldmakeit look more organic.

VUE6's area,Whether or not anyone knows it, Is HUGE; One time, I imported a model of the Executor starship(Darth Vader's personal stardestroyer) and that thing was GIGANTIC,Without shrinking it down it took me allmost half an hour to find my way out of the model; I then put in a 400X400 terrain with palm trees, When that came in, It looked like a grain of sand,I would'nt have found it if it was'nt for the 'XYZ'arrows, Had to blow the terrain up 10 times it's size just to work with it, I placed it on top of the starship and it still looked like a tiny breadcrumb; I agree with Lookoo, Also, I love making my VUE6 and Terragen worlds huge and vast; The eye of the beholder loves to explore, the problem with that is IMHO when the eyes conquer the image and comprehends the size of the area, Reaching the image's limitations...That's it. When I saw your image, My eye wanted to look behind the mountains to see what else there was(Do some exploring) So they were limited by the mountains. Yeah, Work with the haze and the mountains and put a mountainrange behind that one, And another one behind that one, And another one behind that one, VUE6 can handle it,Just go easy with the vegetation and the Eco-Systems.

I hate doing terrains, they never turn out how I imagine them. My main niggle is I wouldn't expect snow covered peaks to sit so close to a such a flat and verdant plain of fields. Perhaps the green area would be a steep sided valley in the foothills of the mountains, or the mountains would have to be further away.