[CentOS] Selecting a Desktop

Folks

Some of my users like GNOME, some like XFCE, and there's even a MATE lover out there. And some would like to change desktops from time to time. Is there some way to allow a user to choose her own desktop? I can envision at least two ways this might be done:

1) Present a user with a command-line login, and have a program (let's call it 'gui') so the user could type in "gui g" for gnome, "gui m' for mate, and so on.

2) Present a uses with a gui login-in screen, which also includes a desktop selector.

Of course, it would only offer those desktops which are installed.

Is there such?

Gui-Confused

David