My particular favorite is the Wednesday evening MORE Hills and Sound Views series, which leaves from Lower Woodland Park at 6pm. I have been bike commuting for over 12 years now, but had only been on one "for fun" bike ride before joining the Cascade Bicycle Club and trying out CTS and the free bike rides. I am so glad my friend and coworker encouraged me to sign up for CTS, and I am happy to have found the MORE Hills and Sound Views group to join for a weekly training ride.
The views can be quite lovely on these rides, since we go up so many hills.