Disregard Seattle. Lived here for over three years, and I still feel like a visitor. The social dynamic is... Swedish. Not to disparage the Swedes. But it's really chilly. Also, the city is so spread out that it feels more like a series of isolated boroughs, and none of those boroughs feel quite as culturally developed as you'd expect from a city this size. And the local music scene is really narrow- if it's not garage punk or cabaret, forget about it. Honestly, I feel like Seattle has got an inflated opinion of itself.
Grew up in Portland- that place was awesome as a kid, and it's only gotten better, although the job market is tough. Warm people, incredible culinary/bar scene, good music for days, and some beautiful (and affordable) neighborhoods.
If you're looking at Detroit, you should check out Baltimore as well. Fantastic city.