I've been using iRender nxt for many years now, and I'm constantly tweaking my settings to create that perfect image... I do now actually believe I have found my ideal set-up.
I space plan and design office layouts for a construction company in the UK, and my work is predominantly based on internal spaces, so my images tend to be set during the day, occasionally with lighting or I'll rely on natural daylight.
I usually leave my computer running over night when rendering the images, so I'd say they are usually processing for about 15-17 hours before I return to work.
I've attached some examples below...
I wouldn't class my PC as a "super computer" either, but it does have what I think is a reasonably good spec...
Core i7 CPU @ 3.20GHZ with 32GB of RAM.
I'm not saying these are the definitive settings for creating internal visuals, but I believe they do create a visual that with enough passing time, will produce something very photo-realistic and could maybe assist new users with a good starting point.
I'd love to see what others are creating and to see what settings you are using.