I would try to think like if I were taking a real picture in the real world. What focal length would be needed, it depends on the kind of scenery lying in front of you. If a white sandy beach, Vue's defaut 35mm can be good, but if a rocky desert or a landscape with many interesting points of view, I'd go for 28mm, which is considered  a wide angle shot, and is vastly used by real camears, so this would look natural to the viewer's eye.
Of course, there's always the panoramic view, and if you want to go this way, you don't need to worry about anything, Vue will take care of it by selecting panorama in the render format. Just be sure to keep the camera steady, or you'll get distortion.