Vancouver Amtrack Station
Coming through the Vancouver Amtrack station may be somewhat easier than the Portland station, however you would miss pedaling through Portland and its myriad of bike lanes. Don't get me wrong, the ride from downtown Vancouver to the 205 bridge is pretty, but isn't particularly well marked. And, I would only use this routing if you wanted to continue into the Gorge via Marine Drive (which you could also do from downtown Portland). I would let everyone on the thread know which route you were interested in and then we could all better help you around any problem spots.