American Airlines operates multiple daily nonstop flights between Dallas/Fort Worth International Airport (DFW) and Seattle-Tacoma International Airport (SEA), offering robust schedules and wide connectivity through its DFW hub. Alaska Airlines is strong on the Seattle end with competitive fares, good service for West Coast routes, and useful Mileage Plan benefits. Delta and United provide one-stop options via hubs like Salt Lake City, Denver, or San Francisco—these can be helpful if nonstop inventories are sold out. In December check baggage fees, change/cancellation policies, and elite benefits; Alaska and American often have the most nonstop frequency, while Delta and United may offer cheaper connecting fares depending on sale activity. Book based on priority: convenience (nonstop), price (connecting), or mileage accrual (loyalty program match).