Ok I have a problem. I'm pretty new to keying footage in general and I'm using AE to key out a lady in front of a poorly lit green screen. The majority has been keyed out using a difference matte which seems to work pretty well. But her hair is really light and on the top and one of the sides it just disappears whenever I key out the reset of the remaining green with a color key. It's definitely spill and I'm using the spill suppressor on top of the difference key and a regular color key. It's just a real big pain. I'm wondering if there is any way I can tell AE not to touch her hair/head.

As I see you have tried most of the keying tools. Perhaps some additional plugins would help. The right lighting is very important if you are shooting against a blue/green screen. Check out the following:

Creating Motion Graphics with After Effects: Volume 2: Advanced Techniques, Trish and Crish Meyer.
http://www.amazon.com/Creating-Motion-Graphics-After-Effects/dp/1578202078

and

Creating Motion Graphics with After Effects, Vol. 1: The Essentials
http://www.amazon.com/Creating-Motion-Graphics-After-Effects/dp/1578202493/ref=pd_sxp_grid_pt_0_0/104-6021585-3728702

In one of those books the Meyers are discussing the hair issue.

Good luck

Margus