Hello, IFC,
I have been spotting for over a year at KSEA, and I found some pretty sweet spots! Here is a spotting guide for the airport.
Note: I will probably update this topic over time
KSEA is a very difficult airport to spot at, since there are no specific locations like at KLAX or Zurich. However, there are some places that work as nice little spotting locations!
These locations will be put in order from my favorite to my least favorite.
1
The Public Water Facility at North Sea-Tac
Pros:
This place is nice for many reasons. First of all, it is a park with a large grass area.
You can see planes on short final and the planes lining up for takeoff at 16L. Sometimes, you can see the touchdown smoke, but not always. With large arrivals on 16L, they fly right above you.
Cons:
This location has a few trees in the way, and in winter, the park is fairly muddy.
Pictures taken at this location:

2
Starling Drive
Pros:
This nice little unbusy street is right at the airport, a few feet from the touchdowns at 34L. You get a few feet from the aircraft, you can clearly see the touchdown (and hear it) and you can see larger arrivals fly across Mt. Rainier (a beautiful local mountain)
Cons:
This place has many tight fences, so I recommend bringing a ladder or stool (or shooting through the fence like me). This location is also a private drive for rich people going to their private jets, so if you become a nuisance, you will be shoo-ed out.
Pictures taken at this location:
3
Delta Cargo Parking
Pros:
This location brings you 5 feet away from parked heavies (A330-300, -900, A350, 757, etc) and has a great view for precise shooting! This is a calm parking lot where you can take close-ups of aircraft.
Cons:
There is a fence, and the exit is easy to miss. The road is quite hidden. You can’t see takeoffs or landings, just parked planes, and keep in note, sometimes this location is empty!
Pictures taken from this location:
4
North Seatac Park.
Pros:
This is a park, Wow! What a surprise, right?!?
They also have a playground and BMX. You can see aircraft on final for runway 16R,C and L and you can have some fun, too!
Cons:
The park is kind of lightly sketchy, and there are trees in the way if you go to the wring spot. If you go to the right place, the trees yield a perfect path for shooting.
You can’t see touchdowns, and the park may be muddy in the winter
Pictures taken at this location:
5
Angle Lake Park
Pros:
This is also a park! Ya don’t say?!?
This place is nice if you want to have fun while taking a few pictures, but really isn’t the best for spotting. This is better if you’re coming with kids/family or on a hot summer day.
Cons:
There are trees in the way, and the park is fairly far from the planes.
Pictures taken at this location:
Here is the map for the locations:
Thank you!
Remember that KSEA is great for variety and rare liveries, but you should bring a telephoto lens or some zoom.
Oh, and a Birb for @anon38496261
Thank You!
Robertine