OK, rode to Auburn today using the Duwamish, Green River and Interurban trails. I can now provide an empirical analysis of these trails.

Duwamish from the WS bridge turnoff is good. It is more clearly marked than I remember. New users should have no problems with this route. It lead me right to the -

Green River trail. This one is a little dicey in some spots. At S. 93rd, 14th Ave So (part of the Duwamish trail) becomes W. Marginal Place S. and you are now sharing the road with autos. Little to no shoulder. Only a few cars did I encounter, at around 3pm. This dicey section is short and the beginning of the GRT is clearly marked and I say clearly because I am not that bright, am easily distracted and if I found it anybody can. This trail is bumpy in some spots, from tree roots. GRT connects with the -

Interurban trail after you pass the U of Pheonix and Embassy Suites. You go over the Green River. IUT is easy, after a short spell is is pencil-stright and fairly seamless, with a few crossings at busy roads but the signal lights are quick to respond to requests for green lights in your favor.

I turned back at 37th as daylight was fading and no part of the IUT or GRT south of the industrial area is lighted. I saw a few other cyclists which helped reassure me I was still on the right track.

Lovely ride.