I was going to mention Elementary OS, too. It is essentially Ubuntu, but with the Pantheon DE. Don't try running it (or Unity) inside a VM though, unless you

I was going to mention Elementary OS, too. It is essentially Ubuntu, but with the Pantheon DE. Don't try running it (or Unity) inside a VM though, unless you like having input lag. The best DE i've found for a VM is either MATE or LXDE. XFCE isn't bad either.