Oh, I think I have a vague request for backgrounds/themes, if you're looking for any direction on it. I really like the kind of fuzzy, sluggish feel of the Sunset theme. It feels very soft and non-distracting. I think landscapes work really well, and so do the warm, non-abrasive colors and simplistic views. A lot of the animated backgrounds have a lot of "information"--faces, fish, TV static, mushrooms growing and dying. The fuzzy/pixelly quality, coupled with being mostly silhouette (and so very short on details), really works for me.
A warm color scheme is also great for latenight writing, for what it's worth. It's why I mostly only use Fireplace and Sunset (and Waterfall, which admittedly breaks the pattern). I'm sure it's hard to make/acquire these, though! This is just one user's thoughts.