Try it for a couple years, you might never leave. Not everything is an exercise in optimization. You could plus/minus yourself right out of the most magical place you'll ever live.
Cons, because you asked and because everyplace has cons:
Greyer/rainier/mistier than most places, colder and snowier than some.
Related, it can be hard to see much of the sky sometimes, with frequent overcast or moisture combined with everygreens everywhere. You may sometimes feel you're living in a green maze and can't see for long distances. But there is plenty of open space too.
Housing is more expensive than the midwest.
Traffic in Seattle is terrible during commutes if you have to cross Seattle North/South or cross the lake.
Pros, because I used to live there and miss it:
You will never run out of something to do or somewhere to go.
It's beautiful. Stunning. Seattle is on Puget Sound, a giant inlet leading to the Pacific, but protected from waves and water violence. You can take ferry rides all over the sound. On some days the water is glass, the sky is unbelievably blue, and Mt Rainier is large and looming no matter where you go. Gulls surfing in the ferry's air wake, killer whales, kayaks and boats and ships of all sizes. Giant drift wood, and charming houses and evergreens right up to the shoreline.
It's so green that moss grows on arterial roads in the shade.
There's a lot of old buildings and new, and lots of neighborhoods are still identifiable as distinct neighborhoods.
Archie McPhee.
Green Lake.
Lots of higher education, UW and PLU and others, and all the spillover that comes with it. It's not Stanford, but it's good, and widespread throughout the Sound.
The Cascades Range to the east. Skiing in the winter. It's not consistently dry powder like Colorado, but it's skiing. Lots of places to ski Nordic; they leave the logging roads open for Nordic, and you buy a cheap sticker for your car to pay for the porta-potties in the parking turnouts.
Hiking in the spring and summer.
Kayak camping in the San Juan Islands.
The Olympic Peninsula to the west, including the Olympic Rainforest, and a very rugged west coast facing the Pacific.
A great skydiving community (start with Snohomish and/or Kapowsin), and if you just like to fly it's an incredible view, a line of volcanoes and ranges from British Columbia to Oregon. Lots of little lakes besides the Sound itself, looks like green and gold and blue coins sparkling on a green rug.
There are no snakes in Western Washington.
Farther east is Eastern Washington, essentially desert. There are snakes
To the North is British Columbia. Victoria, Vancouver. Cruise up the Inside Passage to Alaska.
You should go.