Favorite thing about Seattle that you can't find anywhere else?
Other than that particular mix of Scandinavian and Japanese passive-aggressivity? The Future Is 0—if you're lucky enough to be in Seattle when they have a performance. And Scarecrow Video—though I don't know why a visitor would need a video store other than to show their children the old-timey way we used to view content (by talking to super knowledgeable staff about movies instead of looking up reviews written by Korean robots).
Favorite places to eat, drink, and play in the city?
Northwest Film Forum and Grand Illusion Cinema.
One thing a Seattle visitor shouldn't miss?
The collection at Collections Cafe at Chihuly Garden and Glass. Not that there is anything wrong with the museum next door, but the cool stuff in the restaurant is.not to be missed. (I've never actually eaten there, but I hear the food is good.)
Something in Seattle most people don't know about?
If you are on a busy street corner at a red light in downtown Seattle and there is no traffic, no one will jaywalk. But if you jaywalk, they will all follow you.