Day 4 - as proposed - begins in Victoria i.e. requires a BC Ferry ride i.e. it is even longer than 14 h!

I suggest a re-do, bearing in mind the ferries. There is excellent ferry service from downtown Victoria-or-Sydney to Seattle-or-Anacortes Penninsula. BC Ferries, by contrast, is expensive and somewhat unreliable e.g. $50 res fee for a car -or-wait 2 h in a line waiting!

In Vancouver, challenge the kids to do The Grouse Grind. Its a tough hike, but the views are worth it, and the workout is incredible.