I would suggest stopping by Ken's home. He's got all sorts of packs including GG, ULA, etc. :-)
Alas, there is no one in the area carrying Gossamer Gear. Your only choice is to order a pack. Luckly GG has a good return policy. I have suggested to Nick at Downworks in Santa Cruz about carrying some GG items, but he wasn't sure at the time that it would make sense. If you stop in there, indicate your interest. If three people walk in singing the same song it might be a movement.
The two best places I have found in the bay area to try on light weight packs is the Berkeley REI and Downworks in Santa Cruz.