All of these themes that have currently been posted are, as Palem calls it, bare-bones minimum. They take out "all the flashy images" as he says. But I like those "flashy images." As a matter of fact I think this game could use some more flashy images.
I don't really have a good grasp on what to ask for, but I know that plain bland white (or even dark/black) background is just too boring for me. I'd rather use the default theme than any of the ones anybody has posted so far.
I say this to give you something else to think about and try besides just making it all plain and, as I would call it, boring.
The person with the Facebook suggestion has my vote. I like the blue and the modern style. It's very similar because it's got stationary columns with a column that scrolls which is really the same idea here, but Facebook is far more this decade.