Starting Gnome Automatically with SystemD

I used to start x by just "starting X" - meaning, running startx on the terminal, or putting a script in rc.local or init.d.

But now that SystemD is in play, here is how you do this:

systemctl set-default graphical.target

This is handy if you need to spin up VMs with minimal installs and then add a desktop manager later on.  I had to do this because I needed to access a KVM host with virt-manager. Yes, there's a way to do EVERYTHING on command line (or with CLI). But I like the GUI for this.

NOTE: To install Gnome on a box that did not even have X on it, I used:
yum groupinstall "GNOME-desktop"