Please know, roundtrip Seattle cruises are often higher than North or Southbound cruises. Choose not to get stuck on one concept, like roundtrip Seattle !
I just priced a Royal Caribbean cruise for a caller in a balcony. From Seattle was $ 1700+ and Southbound was $1200+. $500 pp savings to invest in airfare to do Southbound, which offered a better glacier, more time in port, and did not leave out Ketchikan.