Styrofoam, paper, clothing, hair plastic bags...those are about the worst static generators...also to people who run these things on static bags...they are conductive (otherwise, they wouldn't form a Faraday cage).
all depends on the bag type. most of the "cage" type bags are layered in plastic, so you will not create a circuit loop, aka no metal is exposed.
also you would want a humidifier for that. ESD is more prevalent in rooms with very low humidity. dry air breeds friction.
i like the guy who said one of the worst things to put a motherboard on is metal. do you have an acrylic case by chance?