The first is that Seattle is a very bike friendly city, with bike lanes and wider shoulders for cyclists. Riders use them and drivers don't.
There are lots of people on bikes. In the city I am seeing a lot of urban hybrid bikes, cyclocross bikes and... oh help us... the fixie. If there was ever a city that should discourage fixed gear bicycles it should be Seattle... ok... San Francisco and then Seattle. These hipsters seem to be doing more walking than riding up and down the hills. Lots of waterproof pannier bags.
People ride with a little more aggression, purpose and authority on the street as if they belong there. Predictable traffic gives riders confidence.
Lots of Kona, Masi, Jamis, Trek, Specialized... and oh so much Bianchi celeste colored paint. More alloy and steel over carbon fiber. I haven't seen a CF bike yet. Lots of places to lock a bike too.
Bikes are everywhere.