Since I live right off Corn pass... it really is a nice option to hit up Sauvie Isle if it was bike friendly.
The only route not mentioned was Old Corn Pass. Haven't done it recently but that was my error when I came off Skyline.
So the trek for me could be 185th to Germantown and Old Corn Pass to Skyline... and then down McNamee or Newberry. Rinse, repeat or mix it up for the ride back.