The Canadian Platinum does not include any supplementary cards in the annual fee. Supplementary Platinum cards are C$175 each, and supplementary Gold cards are C$50 each.

Don't forget to also take into account any sign-up bonuses. For example, while the Canadian card costs C$699, it comes with two C$200 travel credits and 60,000 MR sign-up referral bonus (worth C$600 in statement credit) in your first year. So even though you're paying C$699 you're getting back C$1000; before even looking at Priority Pass, Marco Polo Gold, etc.

It really is difficult to compare Platinum cards across markets because they just don;t offer the same things. While I would like to have the no-forex fees and big list of MR transfer partners of the USA card, I think all-in-all C$699 for the Canadian card is a better deal than $450 for the USA card. I suspect the same might be true in other markets.