From Sea-Tac: the train works for Pier 66, not Pier 91
Sea-Tac airport is about 15 miles south of Pier 66 and 18 miles south of Pier 91. The cheapest way in is the Link light rail: the station is a 5-10 minute walk from baggage claim through the parking garage, a ticket is $3, and Westlake station downtown is about 40 minutes and 12 stops north.
From Westlake it is roughly a 15-minute walk down past Pike Place Market to Bell Street and the pedestrian bridge into the Pier 66 terminal - fine with a roller bag, harder with three. No train goes near Pier 91, so the usual move is light rail to Westlake and a rideshare from there, which one guide puts at $20-25 against $75-100 for a car straight from the airport. A taxi all the way runs about $40-55 by another estimate.
Parking depends on which pier you're at
Each terminal has its own operator, and the Port of Seattle points you to them rather than selling parking itself. At Bell Street (Pier 66), Republic Parking runs the garage, listed at $33 a day in a parking guide checked in October 2026. At Smith Cove (Pier 91) the on-site lot is tiered - the same guide gives $187 economy, $220 standard and $329 premium or RV for a 7-night cruise, with a shuttle to the ship included. Off-site lots that shuttle to both piers came in around $28 a day.
The Port also lists a Port Valet luggage service run by Bags Inc., which is worth a look if you're doing the light-rail route with more than a carry-on each.
Sources: portseattle.org, cruzely.com, cruzely.com