The Port of Seattle (not Norwegian) offers a Port Valet Program at the end of your cruise. Depending on what time your return is and the airline, you may qualify. Luggage is picked up late evening early, send directly from the ship to your particular airline and flight. You pick it up at your home airport. You will receive your boarding pass the day before arriving in Seattle. You board the bus, go to the airport, straight through to Security and your gate.
Do you know how far in advance of your cruise you can book this? I’ve noticed their web page lists very few ships at a time.