I live on the east side of I-205 in Vancouver. The office of my previous job located in the Heathman Lodge area. I took MacArthur West bound and turned right to Andresen (North bound) passing MillPlain and SR-500.
The down hill passed MillPlain was fun and I got a little bit of work-out going home. Pay extra attention when passing the intersections of Andresen and NE 72nd Drive, also the on- and off-ramp of SR-500. Vehicles are fast on the stretch of Andresen but most drivers were courteous and there's bike lane all the way. This may not be the best route exists, but I bike commuted several years without any accident.
I rarely met fellow cyclists on either directions which may be an indication this is not a good route. I met lot more ppl on my way to Portland. But bike commuting in Vancouver is not as common as in Portland. If you own a car, you may want to drive a few times to scout out the route.