Congrats on winning those tickets Sleekjet!!!
As a Canadian who has been to every part of my great country, I can tell you that anywhere you go will be great. Let's look a your choices...
Canada's National capital. There are plenty of great museums there and you can take a tours of Canada's parliament buildings. If that isn't your thing across the Ottawa River in Hull Quebec, there is a casino. I have never been to the airport, but from what I understand, it is small, but the spotting is decent; fair number of aircraft movements. Ottawa has a plenty of interesting things to see and do.
Montreal, Quebec: Probably the closest city (culturally) to Europe in North America. It has a lot of history and is a beautiful city. Like Ottawa/Hull, Montreal has a casino. Many of the best cultural events in Canada like the Just for Laughs comedy festival take place in Montreal. Dorval airport is small in stature, but has good spotting and a fair number of aircraft movements. There is no shortage of things to do in Montreal. From Montreal, you can also take a day trip to Quebec city, Quebec's capital. Quebec is very European too and is very beautiful
Toronto, Ontario (my home town, and Ontario's Capital):
The most American of Canada's cities, Toronto has many touristy things like: the CN town, the world's tallest free standing structure; The Skydome, the world's first retractable roof stadium, the Hockey Hall of Fame and many interesting world class museums. About 1 hour down the freeway, you will find Niagara Falls, the nice tourist town of Niagara on the Lake and the Niagara wine region; home of some of Canada's best wines. Toronto's Airport is the busiest in Canada, so it has a lot of movements and great spotting. Toronto has lots of things to do.
Is one of my favourite cities in Canada. Depending of the time of year, you can visit the Calgary Stampede, which is one of Canada's most popular events. I don't think it would be unfair to describe Calgary and Alberta as a whole as being a fair bit like Texas (Some people may disagree with me here, but that's sort of how I see it
) You can also visit the old Olympic site from the '88 Winter Olympics; all of the venues are still up and standing. If you like skiing, Lake Louise and other great skiing opportunities are a couple hours to the west in the Rocky Mountains. Calgary has Canada' fourth busiest airport, if I am not mistaken.
Vancouver, British Columbia:
Canada's most beautiful city and my personal favourite. There are a lot of great parks and beautiful mountain landscapes to see in Vancouver. There are a lot of great touristy places to see and a lot of things to do. About an hour north of Vancouver you can go skiing at Whistler. Vancouver also has a lot of opportunities to golf, if you are into that. Vancouver also has the second largest Chinese community in North America, second only to San Francisco, and China Town is an interesting place to visit. If you go to Vancouver, you should visit Gas Town, which is neat. From Vancouver, you can also cross the Georgia straight and end up on Vancouver Island and visit Victoria, British Columbia's capital city.
Or you could always take Mcdougald's suggestion and take a train trip From Toronto to Vancouver. This train is called the Canadian, and gives you a great perspective on just how vast and majestic Canada truely is, taking you across most of the country. This is one thing I have never done, but I really want to.
To be honest with you, if I had to choose a place to visit in Canada, I would have a hard choice as everywhere is great. I know I haven't made your choice any easier with my post, but no matter where you do end up visiting, you will have a great time!!! Every place in Canada has very friendly, polite people who will make you feel welcome!!!