I haven't done the work that you're asking about, but I checked out a piece of software called OnOne MaskPro and another one called Vertus Fluid Mask.
I preferred the user-interface of the Vertus tool, and it made pulling like-colored items out of a background pretty straight-forward. There is the notion of "keep", "don't keep", and a strange nether-region called "blend" that is user-controllable. The "blend" region is what really makes these sorts of tools shine IMO. These are not the official names of the features BTW.
This is from my post-processing crib sheet:
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Train the Quick Selection Tool -->
http://tv.adobe.com/watch/photoshop-...election-tool/