Seattle is an often-underrated, kick-ass city. My company is headquartered there, and I get to go about 3x a year. Never got the impression it was much of a metal city, but still fun as hell nonetheless.
Go to a Mariners game. Safeco Field is awesome. If you enjoy decent beer, Seattle's certainly got its share of top-notch brewpubs and beerhalls. If the "LA scene" is your thing, Belltown is a great place for nightlife (i.e. trendy bars/lounges/clubs, excellent restaurants). And I've never visited a city with more to offer in the realm of outdoor activity. There's so many places to boat, swim, hike, bike, etc., it's amazing.
Good luck. I'll be there next week myself!