KDE Neon should ship with the plasma-workspace-wallpapers package by default, which will provide a nice assortment of pretty wallpapers. Also, this package should get better and prettier over time due to D17780 and T10220.
Manjaro's KDE version already installs this package by default, and I've proposed that Kubuntu do likewise: T10218. As a KDE showcase distro, I think KDE Neon should too--especially the user edition! But probably the developer edition too.