Free Texture Downloads for 7 days
Finding free high-quality textures is always difficult. Here's a great resource...once you sign up, you get to download 20 free images a day for 7 days. I just tried it today...had luck finding some good wood flooring images, which always seem to be hard to locate.
The best tip for searching on this site is to put in the search terms "seamless texture". I also like to use just textured backgrounds to "paint" my rooms with. If you scale them correctly, they can just look like plaster or faux finishes, and they have much more depth than just painting on a solid SketchUp color.
Here's some wood floor examples I found....