There are a lot of breweries in the Seattle area, but they tend to be far from where I live, work, or otherwise spend time and thus I don't visit them as often as I should. Which ones have you visited? Which ones do you feel are specifically worth a visit vs just getting their beer elsewhere?
My own experiences:
Black Raven in Redmond is great. They've got my favorite IPA in the area (Trickster) and everything else they brew is at least an above-average example of its style. It's a nice place to sit around and drink, despite what the outside may lead you to believe. Flying Saucer will deliver pizza right to your table if need be.
Two Beers hosted an event with Tako Truk earlier this year, but I was there more for the food than the drinking. The special beer they brewed for the event wasn't very good, and the inside is definitely not designed to be a place to linger (I can't necessarily fault them for that, but still..). Maybe it's better on a normal day.
I went to Schooner EXACT for a Seattle Beer Week event and really enjoyed the smoked ESB they were pouring. It seems like a good place to drink outside on a sunny day, and even the indoor bar gets a lot of light when the doors are open.