Wind speeds tend to slow down near the ground due to interference. Buildings, trees, hills, grass, etc., all help in blocking or interfering with the flow of air. So, it will usually feel a lot less windy if you're standing at the base of the Space Needle than if you were standing on the observation deck.
On the other hand, building can sometimes funnel air between them, increasing the wind speeds. That's why it can be a lot windier while walking the streets of downtown Seattle, as opposed to flatter, residential areas.