What do you use for your desktop background? Lock screen?

What do you use for your wallpapers? I've been using Bing Desktop, which changes your desktop background every day to the lovely pictures provided by Bing (they also do the daily pictures on your Lock Screen before you log in). I would say many users I see (I work in a Microsoft Store as a Services Advisor) usually have some place they went on vacation or a picture of their family. I've even seen some people have a slideshow as their background, to change to different pictures on an interval.