The greatest challenge when it comes to backgrounds is that you need to show proper restraint. A background is just that... a background. Would you expect to see a gaudy patterned print at an art museum? You need to find the proper balance between an interesting background and preserving visual hierarchy of information.
We understand why the problem exists. As the stock animation industry has grown, competition has led to more and more companies trying to "stand out." This means that designs have become busier, louder, and generally obnoxious.
In contrast, let's look at the print industry. Sure, a designer might use a patterned paper or a colored backdrop, but never in a way that negatively impacts the readability of text or diminishes the value of a photograph. Creating a background is truly an invisible art. The goal is to make something that adds to the overall design, but does not stand out.
This is from Motion Graphics with Adobe Creative Suite 5 Studio Techniques
Get it here – http://www.amazon.com/exec/obidos/ASIN/0321719697/richardharrin-20/