I agree with Donna - check with your agent and they should be able to help you.
Because there is so many variables involved in 'pre-cruise' excursions, in situations like this, it's not unusual that the cruise line doesn't offer them. This is why it would be better to utilize an independent company or to do your own thing. Depending on when you're getting into Seattle and how much time you have, you may find it better to pick out the places you want to visit and just take a taxi or do the Hop On Hop Off bus, which we really like.
Travel Agent/Cruise Specialist w/12 yrs exp and 47 Cruises on 11 cruise lines! Favorites: Paul Gauguin - Tahiti: Uniworld River Cruises - Europe; Celebrity Solstice-class ships; Holland America - 12-nights Baltics & Russia; RCCL - 14-nights Greek Isles, Turkey, & Croatia; Holland America - 14-day Alaskan cruisetour; 10-night Canada/New England cruise; 21 days Hawaii w/7-night NCL cruise; Oceania - 25 days in Asia; more than 3 months touring Europe by train. And many all-inclusive resorts!