Hello I just found this myself in Ubuntu 12.04.1 LTS
click on "unity dash" and type in the command line "power"
open power options by clicking on power icon in unity display screen
ensure that lid closed option is set to "nothing" THEN click on brightness settings link under where it tells you how much your battery is charged.
in the new window called Brightness and LOCK - you can turn off the lock option (which I assume is the suspend since we already set close lid to do nothing in power options
My favorite option in this page though is the check box require password when waking from suspend. Remove this, and you never get prompted for a silly password after closing the lid on your laptop
Hope this helps