Interesting work, looks pretty good. Nice stones, they are FrankB's stones from NWDA, aren't they?
I have a couple of suggestions for improvement if you don't mind:
The trees are all standing perfectly straight which looks kinda boring imho. In the object maker give them say 4 degrees rotation on X or Z so they will all just not stand straight up.
Also there seems to be a bit lack of size-variation which together with the straight trees gives a very monotone look.
Renderwise I think it's a lot more interesting to have your new monster machine flex his muscles on renderquality rather than huge ass resolution

Try something like AA32, set to 1/16th first samples and pixel noise threshold 0.15 or 0.2. Set atmosphere samples to 8 and enable RTA.
For GI choose 2/4/6 with SS-prepass, but no surface details.
With these extreme AA settings, which are perfectly render-able on your 2600K you can get awesome results with the cubic b-spline AA filter, which normally is inferior at lower settings.
Try it!

Cheers,
Martin