The Shamrock Run PDX is a staple of the Portland running community, and I am a happy staple of the 15K runners. The 15K is the perfect distance for this event. It includes the whine-worthy Terwilliger MOUNTAIN without the Naito out and back the half marathoners have to complete. Its long enough to really enjoy a beer, a burger, or whatever else you want. And the distance is a confusing enough length that folks think…