Aaron - FYI (Tanasbourne into PDX route) the Winthrop Park/Willowcreek trail is fine when it is dry. When those wooden walkways get wet, they are incredibly slick.
I prefer to go (heading east) NW Evergreen, NW Cornell (I think the construction may be complete in my lifetime, but it is rideable.), R on NW 158th, 1st left (TAKE THE LANE), through the office park, through the Tualatin Hills Park and Rec,
Pioneer, R on Meadow, BL on Butner, cross Murray, R on Huntington, L on Park Way.