Cascade Bicycle Club runs a bazillion rides weekly at all levels--always worth checking out. The local Luna Chix also lead weekly rides: http://teamlunachix.com/seattle_cycle. And Cycle the Wave, a women-only ride in September, is running a summer training program designed for its 25-mile route: http://cyclethewave.org/. And, by the way, the Cycle the Wave event in September is a total hoot.
"My predominant feeling is one of gratitude. I have loved and been loved;I have been given much and I have given something in return...Above all, I have been a sentient being, a thinking animal, on this beautiful planet, and that in itself has been an enormous privilege and an adventure." O. Sacks