Here, on Kate Winslet, is pretty much the perfect updo.
There's a deep side part, which softens it up, and the bangs fall ever so gently over one eye. The hair has a bit of a wave (texture—even frizz—is the next big thing in hair this year). And the bun sits fairly low on the head, which keeps it effortless but still sophisticated.
There's something about high buns that I dislike... possibly because they can so easily look like Bridesmaid Hair. And you know that if I'm capitalizing that phrase, it's not a good thing.