Air Canada is looking to bulk up its international traffic from U.S. customers. Its lure: a free stopover in Toronto for as long as seven days. So if you’ve yearned for a week in Canada’s financial and cultural hub and are flying to Europe or Asia, this is the deal for you. The free stop is available on higher-priced coach fares as well as premium economy and business class prices so long as you book your flights by December 31. A warning if you’re not a regular Air Canada flyer. Do not book any flight marked Air Canada rouge. Those are flights configured with densely packed seats and a reputation for being the Canadian equivalent of waterboarding.