Think we can find sweats in nice tropical prints? :-)
As true native Washingtonians know... "layering" is the key. At least 3 Layers of clothes, going from light to heavier out to an outer shell of something rain-proof.
You take off layers or put layers back on depending on what the weather is doing *right now*. The rest goes in a small backpack (see REI online catalog for details).
For example: Yesterday it was cool... about 55 or so. I was wearing my heavy CC Filson thick wool jacket just to go outside for smoke breaks. In the afternoon it cleared off and warmed up and I was just out in a polo shirt. Today it is about 70 or so, and I'm driving with the top down. Total blue sky... didn't even have to worry about putting the top up to come in to da waterin' hole.
Like they say: The great thing about Washington is that if you don't like the weather... wait five minutes. It'll change. :-)