I like the 2x3" Ziplocs because they only cost 1 c ent each from Wal-Mart.
They give room for lots of text on a paper llabel, and let you read the label THROUGH the Ziploc. And they are easy-open, easy-reclose. For some seeds I'll use 1.5"x1.5" Ziplocs, to save space when I don;t have a lot to write on the label.
Plastic that thin (1-2 mils) actually does let a LITTLE humidity esacape SLOWLY, right through the plastic (so says Drierite). And I believe that humidity escapes even faster through the Zip closure, which is clearly not heremetic. I often find that I can squeeze a little asir out of Ziplocks even after they are closed!
Here are some of my favorite online sources for Zippies, but it is hard to beat Wal-Mart price of one cent with no minimum order and no S&H!
http://www.clearbags.com/cryst...
http://www.uline.com/BL_208/2-...
