A nice grade of muslim will work great. Also, as far as the pens go. I've used:
Pigma - not crazy about the tip on them, find the fine tip on them makes it hard to write with.
Y&C FabricMate - Works well, just have to make sure the tips are solid and if written with too hard they'll bleed (probably wouldn't work well with a group).
ZIG Memory System- Found these in the papercraft area. Absolutely wonderful, ballpoint tip makes for very easy writing (no drag as with the Pigma). They're Photo Safe, Acid-free, Archival quality, lightfast, waterproof, fade-proof and non-bleeding. Will end up purchasing these in more colors.