I hear ya totally on that one, and have been wondering the same thing myself, since I also grew up in Washington State (I live in Shelton, WA).

Several errors in terms of Washington State scenery are present as far as I can tell, outside of the list I mentioned in a Flight Simulator 2006-related thread.

The Tacoma Narrows Bridge towers are 119 feet taller in FS9 than it is in reality - and its towers are too close to land especially the West tower, which does not sit on land as it does in FS9. In reality, the West tower is 1,100 feet (or the length of its sidespans) offshore, while the East tower is approximately 900 feet from shoreline.

The layout of Seattle Center is way off. The Pacific Science Center should be right under - and just to the southwest -of the Space Needle.  Experience Music Project is too far south (KOMO TV's Fisher Plaza building occupies the spot in reality).  Memorial Stadum (for those not familiar with Seattle, Memorial Stadium is adjacent to the Space Needle) should be positioned at least five hundred feet further north, and Key Arena needs to be considerably larger since it's a prominent Seattle skyline feature.  And The Space Needle itself is over 100 feet taller than its real-life counterpart.  The mast is 605 feet above Sea Level. In FS9, it's 771 feet.

IIRC, and I'm going to experement with it a little, but I believe that by using the Scenery SDK, you can modify the scale of any given object.

But, once MegaScenery Pacific Northwest comes out in January (I hope!), we won't need to do such modifications. MegaScenery correctly places (at their correct scale as well) all major scenery objects and corrects the placement of all airports covered in the scenery add-on.

I can't wait 'til it comes out.