Having spent a decent amount of time in both Seattle and San Francisco, both are amazing. The traffic in SF is worse, but also way more fun with the hills. And if you like people-watching, San Fran wins hands down, there's freaks everywhere, but any weirdos I talked too seemed like really nice people. it's also expensive as f*** though. Seattle is definitely cheaper, still really nice and I find the traffic really easy. Lots of bridges and tolls though but the scenery is great.