Let's face it - airports aren't becoming any friendlier toward photographers. Carry a DSLR up to an airport boundary fence, and you'll be descended upon and discriminated against faster than you can say "civil liberties". But there are still a few places where you can photograph brand-new 737s without being treated like a felon.
Seattle is one of those places.
Take a walk down 20th Avenue West over by Interbay, and you will occasionally run across views like this:
Here's the Google Street View link.
You can also get some decent shots from the other side of the tracks. Just head to Interbay Golf Center on 15th Ave West:
And always travel with your camera. As Airliners.net photographer Dave Lednicer demonstrates HERE, you can find the 737 fuselages enroute between Wichita and Renton.