How do I set the GNOME Classic login to be the default with autologin?

Run the following in a gome-terminal:

• If you want GNOME Classic with effects:

  sudo /usr/lib/lightdm/lightdm-set-defaults -s gnome-classic

• If you want GNOME Classic without effects:

  sudo /usr/lib/lightdm/lightdm-set-defaults -s gnome-fallback

auto log-in gnome classic desktop :

• sudo apt-get install gnome-session-fallback
• sudo /usr/lib/lightdm/lightdm-set-defaults -s gnome-classic

For Ubuntu 14.04

I followed the post here

Summary :

• Install the lightdm-webkit-greeter package: sudo apt-get install lightdm-webkit-greeter -y.
• Open the /etc/lightdm/lightdm-webkit-greeter.conf file in your favorite text editor.
• Add the following lines to the end of the file:

[SeatDefaults]
user-session=gnome-fallback