Next April the Royal Caribbean ship Rhapsody Of The Seas repositions from Australia to British Columbia. It is done with two cruises. The first leaves from Sydney and ends at Honolulu. Then the ship departs from Honolulu for Vancouver. It is a long time though - 16 days for the first cruise and 10 for the second one.
But it is certainly interesting and you see a lot of places.
April 12, 2010, from Sydney. The ship arrives in Hawaii on April 27 and then turns around and leaves that same evening. (Yes, it seems a day is missing - International Date Line).