The settings for the images in the Planetside Gallery vary quite widely. The only likely commonality is a main Detail level of 0.5 or above, most of the time 0.75 to 1.0. Seldom is detail above 1.0 used, and even 1.0 is often not necessary. For complex vegetation images it can be helpful to smooth out the results, as can High Population Detail (set in the populator), but otherwise I tend to use between 0.5 and 0.75 and get very good results.
Atmosphere and cloud sample levels will also very tremendously depending on the scene characteristics so the guidelines there are really only very general - use 32 or more atmosphere samples for best quality in most scenes. Never go above 128 unless absolutely necessary and you're willing to wait for good results (as an alternative you might consider post-processing the noise). For clouds the Quality slider can work pretty well and should generally be at 1 or slightly above (1.25 for example). I use 32-64 samples for the average volumetric clouds and get good results. In scenes with complex lighting and/or heavy shadows I go up to 128 or 256, but seldom above that. 512 is sometimes necessary, and some very dense and noisy clouds need 1024 but I would *never* go above that. If your clouds need more than 512 samples I would consider adjusting the other cloud settings instead of increasing samples. You will get a faster render and it's likely that with the other settings you're using that are causing high noise, your results may not be that great even with high samples.
Of course both of these areas can be set to similar levels in the free version. The 2 areas where the free limitations probably show the most are resolution and antialiasing. Most people will use 6-12 AA for final renders. With complex vegetation sometimes more will be necessary, but seldom greater than 16.
GI is another area that sometimes gets pushed up, but 2/2 is actually very good for *most* scenes and increasing these settings dramatically raises render time.
- Oshyan
