I lived in OP a while ago, and it was inexpensive and really spread out. I would imagine that housing prices are 2-3x higher in Seattle, so the aggregate cost of living might be higher there. Yeah, it's good to avoid burning a lot of gas, but unless you can do your food shopping on foot, you'll still need the car.

Moving from suburbia to urbia(?) let us get rid of a car, walk to work and do about 40% of our shopping on foot. I'm not really interested in schlepping big packages of paper towels on a bus :-).