Postscript on Blue Heron: I just checked to see what I had used to exchange for an early August week, which I assume is prime summer, and it wasn't an absolute prime week at a top-tier trader, so it may not be that difficult a trade - yes, probably easier than Worldmark Seattle.
BUT if your friend is limited to only one specific week, and is trying for just one or 2 resorts, that slims down her chances by a lot. If it were me, I'd hesitate to cancel the Ocean Shores without another confirmation in hand - does she have another spacebank to search with in the meantime? Then if nothing matches, she could think about Ocean Shores for most of the week, leave a day or 2 early, then spend an extra night or 2 in a Seattle hotel or b&b before the cruise.
For that matter, Victoria could be another alternative for the above scenario. I've seen many summer weeks come up for Victoria that don't require a powerful trader.