CP has 4x daily from Boston to Toronto, and daily flight to Vancouver. 3 out of the 4 flights to Toronto are NOT code-share, they are operated by Canadian Regional F28, which I believe will count towards the bonus. The other is a 737. Flights to Vancouver is on a 320.

Cheapest way is to follow the "Web Special" section on the CP site and catch one of those frequent weekend fare between Boston and Toronto. You could fly to Toronto this weekend for US$ 106, or CAD$ 155. This flight shows up often.