Every day I'm learning something new, recently I started to work in an Architect's office where they use to do very large projects, and I found that those file's projects are very dificult to handle in Sketchup, they use to do their 3d Models in Autocad, so I tryed to make a rendering with SketchUp, and the first problem was that it was very hard to import very large files into SketchUp, then they ask me to find a software to make the renderings, so I used Vue, and that was ok, and I may buy a software for interior renderings that can make renderings from SketchUp, and from 3DS Max, because I use SketchUp for my projects and 3ds Max for their Projects (Those large projects)
In my case, the software i'm sure I'm going to buy is Thea Render, it has plugins for Sketchup and 3ds Max.
I own some of the render engines out there for SketchUp, like IRender, Podium, Twilight, and I have used all of them, for different situations, and different clients.
For me all of them are very good.