PDX sports one "H" shaped terminal which is divided into five consourses, A-E (A, B, and C make up the southern arm, while D and E make up the northern). The terminal is straddled by two parallel 10/28 runways with a shorter, lesser-used 3/21 airstrip to the west. A new parking garage has been built since my last visit, which might provide spotters' with another outdoor location.

OUTDOORS:
-Marine Dr. Along the northern end of the airport, running alongside 10L/28R, is Marine Dr. This road has a large pulloff where you can park your car and watch the action. I've heard, although I haven't see it, that there's a catering truck that will sometimes park there and sell food and refreshments. A great view over the top of the fence you're sure to love.

INDOORS:
-Concourse C, Gate C13. Takeoffs in either direction on 10R/28L are best viewed from here, which is not only the closest gate to most rotations, but is also set up in a way where the windows provide a near 180-degree panoramic view (except form one stubborn jetway which provides a mild obstruction).
-Concourse C, Gate C16. To get a good view of the action on the other side of the field, just head across the same terminal to gate C16. The action on this side of the field is much better when the action is on 28R.
-Any odd numbered gate in Concourses D and E. The north side of the field is easily viewed from almost any gate on this side of the terminal. Concourse E is a bit better than D, but both are great for action on 28R.

PRE-9/11 SECURITY REPORT:
-I haven't had a chance to check out the new parking garage, but given the airport's willingness to provide spotting areas on Marine Dr., I can't imagine security has any problems with people loitering in the garage. The Marine Dr. lot is completely free of security interference. All-in-all, PDX is a very friendly airport.