USA 45th Street Overpass, Seattle

The bridge over I-5 Express at NE 45th Street, which is leading towards downtown Seattle, is a really nice place for sunrise and blue hour photography. It's definitely not one of the best spots in Seattle, but it's a unique one, which is worth visiting if you have a really nice sky. It also offers a nice overview of the city from the north.
You can even spot the Space Needle beyond the trees from this perspective.

This is further from the city so you will need at least a 70mm lens; bring along a tripod, shutter release and set your aperture small for the starburst. This freeway has heavy traffic so a shot in summer is advised when there are fewer cars travelling if you want the car trails.

If you are there for a sunrise photo, just make sure to be there quite some time before sunrise and start capturing light trails before it's getting bright, so that you can integrate these trails afterwards into your final sunrise photo.

If you are here during sunrise, there is parking right beside the bridge where you can leave your car, since the parking place is usually empty during the early morning. There is a bus line too, stopping right beside the bridge.