First off, it may be a good idea to get a reality check about Seattle, and then of course, we'll get to the good stuff. I'm a Seattle native-and it is true, Seattlites are passive. I don't think I've ever had but one close friend ever. I can say after living in crappy-because-I-can't-find-a-job California after a few years it was a lot easier to make friends there. California IS friendlier, but we're debating the good and bad of Seattle here. In Seattle, people are nice in a friendly way, though not actually willing to make friends. Seattle is not the most sociable city (maybe the weather?).
It's a great place to be, though I don't recommend living here unless you're fairly well off or don't mind running into the many hipsters and young trendy couples with 2.5 kids. They are rampant in this town, especially in condo-ridden Ballard.
You may find it difficult to live in Seattle 9 months out of the year if you're from a warm climate. All the stories you've heard about the rainy weather in Seattle are true and then some.
The cost of living is high, and transportation is at the $2.50 per bus ride (and climbing) mark. Rent is high, though still reasonable for a large city (about $900-$1500). There is also a lot of petty crime, and rising violent crime. Traffic is getting worse, so prepare for a commute whether you're in a car or on the bus.
We can't overlook the culture that Seattle has to offer, and the Emerald city offers a lot of it. Seattle has great theater and opera, and it is underappreciated. The seafood IS the best. Wild salmon makes for good eatin'. We have museums, good colleges, and some interesting neigborhoods (check out Fremont). The air quality here is good, and you don't need a car to get around.
All in all, Seattle is just like a lot of other big cities; stressful, but good if you have a positive attitude and some bucks in the bank.
Please do a lot of research no matter what town (or country) you end up in. Good luck!