Currency: The local currency is the US Dollar. Credit and debit cards (VISA, MasterCard, etc.) are widely accepted throughout the city. In some cases, you will find that smaller businesses only accept cash, so it is recommended that you carry a small amount of cash with you.
Time zone: Pacific Daylight Time
Electricity: All power sockets in Washington provide a standard voltage of 120V with a standard frequency of 60Hz.
You can use all your equipment in Washington if the outlet voltage in your own country is between 100V-127V. This is mostly the case in the US, Canada and countries in South America.
Washington uses power outlets and plugs of types A (two flat prongs) and B (two flat prongs and a round earth pin for grounding). Anything that plugs into a Type A socket can plug into a Type B.
More information on Seattle on Visit Seattle and Travel Seattle.