Willow Creek Rd is a gorgeous, quiet and fairly private climb through Western Sonoma County redwoods. The trail is an alternative route back to Occidental, Sebastopol, Santa Rosa, etc. from the Jenner/Bodega Bay coastal areas. While the trail is not paved, it is easily manageable on a road bike (25-28mm tires recommended), other than a .1 mile 22% section at around the 2.5 mile mark which may require a dismount and brief walk.
This climb is highly recommended for its rural and forested charm and should be done at least once in your cycling lifetime if you live in the area.