Hmmm... well, for a more flat route you could go down Scholls to the Fanno Creek Trail, down Tigard St to Main St, and then around Burnham to Hall... But I don't think it's any faster than the route you've already described.
My commute is pretty close to your commute, at least from Gaarde/121st to Durham Rd... It is kinda hilly, but at least on the way in to work it's mostly downhill!
Have you tried going down 99W to 124th and Tualatin Rd?
Or, go all the way down Walnut to Tiedemann, then down Tigard St to Main and all that as described above. It at least cuts out The Wall (aka Gaarde, between Walnut and 121st)...
What time do you hit the road? I assume you're leaving your house around 7-ish to get to work and get cleaned up in time for an 8am start...