Hey David, how can we e-mail you if you have not provided one?
It depends what is your taste.
Toronto is North American city. New, beuatiful, center for banking system and home of CN tower (the highest tower in the world)
Montreal, is the intersection of Europeen and American. Downtown is in no difference from any other north american city but Old Montreal, and Old Port is the reflect of Europeen past of Montreal. The restaurans are great and casino too. Formula 1 is held in Montreal.
Besides, in Montreal and Quebec city you will have an opportunity to meet french women.
Quebec city is totally europeen city. It's an old, romantic city.
Ottawa is quite. Capital of Canada. Logically home of all governamental buildings.
Vancouver is beautiful. The weather is fine. You are not coming in winter. But if you consider staying here in winter, Vancouver is much better place. Vancouver is surrended by mountains, another source of beaty.
Basicly, it depends on your taste.