Not scenery design in a sense, but objects. I suppose it boils down to how you classify "scenery".
What a chore. SketchUp. Nothing like Gmax. Problem being if I want to finish what I started (numerous scenery objects), I am forced to learn and overcome the idiosyncrasy of this program.

Simple structures like buildings, basic shapes, etc, for modeling scenery objects, it's a very usable source for "creating".

More here. http://imgur.com/a/5Yok0#0

Until you get ballsy and try something like this. This model tries my patience continuously due to a (lack of) friendly hierarchy.
Willys CJ3B

There are more http://imgur.com/a/0HpFx