Basically I want to know if ZG enchants are still going to be the best enchants for legs/head & shoulders in the expansion. It's going to be a good deal more difficult to find groups to run ZG I'm thinking. Should I spend some time before the expansion to get voodoo dolls and primal hakkari idols?

Legs - yes, for some classes. Replacement is various kinds of crafted threads

http://thottbot.com/beta?s=spellthread
http://thottbot.com/beta?s=leg+armor

For head slot there is superior vendor bought enchant for every class (i think)

http://thottbot.com/beta?s=glyph

I know that the thread is a monster, but this sort of specific question is REALLY what the generic Q&A thread is for.