I'll agree with Eastbay. Leaving SEA, you get to fly over the northern edge of the Olympics and have a spectacular view of Vancouver Island. Either side of the plane works for this view. On approach into ANC, you'll get to see the glaciers and interesting mud flats south of Anchorage. Heading south is usually after dark for me but I enjoy seeing the city of Vancouver lit up since the southbound flights seem to come into SEA on a more easterly course.
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