If you’ve updated to the new macOS 10.12.2 update you probably haven’t spotted the all-new default wallpaper images. They’re the ones used in recent Apple advertising, so include a wider color gamut for the new MacBook Pro models that support it. In other words, they should look magnificent on the screens of those models – although they look pretty good on any screen.
To get to ‘em, just open System Preferences, click the Desktop & Screen Saver icon, and then ensure the Desktop tab is selected. Then scroll right to the bottom of the thumbnail listing of wallpapers. Note that if your Mac has a trackpad you can use the pinch-expand gesture to make the wallpaper thumbnails bigger.