I'm partial to Calgary. Great large city lots of things to do. You can see the rockies from Calgary and the towns of Canmore and Banff are only 45 and 60 minutes away respectively. Both are world class resort towns nestled in the mountains.
The other one I'd vote for is Vancouver. Lots of stuff there and mountains too. Theres more to Canada then just Toronto and Montreal.
Also one quick note, Edmonton is home to West Edmonton Mall. A person could easily spend a week there alone. Has a huge indoor water park, a large fish aquarium with submarines to ride in, a dolphin show, something like 25+ movie screens, a shooting range, an indoor NHL sized rink, a 'replica' of bourbon street, and a huge indoor amusement park with a bunch of rides including the worlds biggest indoor roller coaster (i believe).