Being a worker in the tourism industry (I work during the summer at the tourism office of my town), Tourism offices provide essential information in order for you to do a great trip. Here are information you can find on official websites of my favorite places in Canada.
First of all, the Montreal Tourism website gives you useful information about the major attractions, proposes you last minute deals, stories, polls, etc. If you plan a trip to Montreal, this website is going to be a great help.
If you want to go in Ontario, the Toronto Tourism websites suggests you special offers on hotels, restaurants, shopping, attractions, theatres, events, festivals, galleries, etc. As for the Niagara Falls Tourism website, it tells you where to stay, where to eat, what to see, etc. You can even take a look at the weather so that you can plan what kind of clothes you will need.
The Alberta Tourism website offers you the possibility to explore the different cities, to experience this wonderful province through arts, attractions, events, outdoor adeventures, etc. Finally, the website can send you for free a vacation guide that will help you to plan your trip.
Finally, British Columbia Tourism website informs you about all the attractions, special offers, special activities and events. You can even find maps to help you.
As you can see, all websites are all pretty similar. But, they are excellent sources of information.