#Seattle Philadelphia, USA - for only $185 roundtrip with Frontier Airlines. DATES: January - February 2023. Example dates: > Seattle – Philadelphia: 6th-13th Jan 10th-17th Jan 23rd-30th Jan 5th-12th Feb 6th-13th Feb > Philadelphia - Seattle: 10th-17th Jan 17th-24th Jan 30th Jan – 6th Feb 4th-11th Feb 6th-13th Feb 6 viewsedited 20:00