Chris, your packs have been a huge inspiration.
Besides the 1.9oz sil (red) I used standard oxford pack cloth for the back/bottom panel, shoulder straps, hipbelt, water bottle pocket and the bottom 4 inches of everything else.
The the front and side (Contrail-tube) pockets are made of Lycra mesh. Heavy, yes, but I like the stretchyness.
I also opted to not use elastic at the top of the pockets becasue a) I ran out and b) the Lycra's pretty much stretchy enough on its own.