There are piles of fantastic rendering tools to choose from, and more become available all the time for Google SkethUp. Shaderlight, an awfully-impressive and relatively new offering from ArtVPS, is one such rendering tool. Its interface is clean and straighforward, there's a free version available and the video tutorials are easy to follow and comprehensive. It's currently only available for Windows, and the Mac version is in the works.
Here's an tasty sample renderings to whet your appetite:
In the interest of fairness to all of our rendering friends, our plugins page lists some of the other tools you can investigate if photo-realism is your bag.
More Info: Shaderlight