Cheap Flights from Washington (IAD) to Seattle (SEA) from HK$1,165~

Start packing your bags, because round-trip flights from IAD to Sea-Tac Airport start from HK$3,031. That's based on fares advertised within the last 7 days on Expedia for flights departing within the next year. Prices can change quickly, so book today to get the best deal. Prices and availability are subject to change. Additional terms apply.

Most flights can be conveniently canceled online, but whether you incur a fee differs between airlines. If you do need to cancel your vacation, follow the instructions in the Customer Service Portal.

Many airlines offer the option to reschedule your flight without a change fee. All you pay is the difference between the original flight and the new flight. When you're searching for Dulles Intl. Airport to Seattle - Tacoma Intl. Airport (SEA) flights, you'll see a "no change fees" filter for you to select.

You'll be in the air for a while, as the flight distance between Chantilly and SeaTac is 3,700 kilometers. Set up a playlist of your favorite songs before leaving home to keep yourself entertained during your trip.

United Airlines (UA) is a popular option. It offers 60 flights from IAD to Sea-Tac Airport each month. Offering 56 flights a month along this route, Alaska Airlines (AS) is another top pick.

It is possible to find a fantastic last-minute deal from IAD to Seattle - Tacoma Intl. Airport (SEA), but it can also be hit-or-miss. As many airlines release seats up to 12 months in advance, it's worthwhile keeping an eye on fares early and being ready to pounce when you see a good bargain. Expedia compares air carrier prices and updates flight deals frequently, so you can rest assured you're always seeing the latest offers.