When creating interior views, the furniture you choose is of paramount importance in establishing the look and feel of the image. While people are not used to discerning the build quality of architecture, they are very well equipped to judge good or bad furnishings. This is because everyone buys furniture, and everyone spends most of their lives inside. So, when you look at an interior visual, most of the impact will be created by the furniture, not the room itself, as you can see in the following image:

This fact gives rise to the continuing need for good 3D models of furniture, much of it branded. Since design houses want their designs to show up in interior visuals, they often find a way to provide free models to us. It's just a matter of finding them.

Before SketchUp came along, most visualizers used 3D Studio (later 3D Max) to create architectural visuals. So, there are years worth of content around the world in the old 3D Studio format, *.3DS. Guess what? Lots of it is good...