I'm not sure if it is something that is specific to my machine or my upgrade path, but when I moved from Mint 15 to Mint 16, suspend would no longer work; neither when closing the lid, nor when selecting it from the shutdown menu. When trying to resume, it would freeze at the login screen.
Changing drivers through the Driver Manager only made things worse.
I didn't figure this out on my own. See the links below for reference.
This is for the 64 bit version. Check the links for the 32 bit. It will update the kernel, then the video drivers.