The CN Tower is the must-see tourist attraction.
The views are amazing - http://www.youtube.com/watch?v=jwvXe_B6nR8&feature=related
On a clear day, you can see Rochester clear across Lake Ontario from up there.
Glass walled elevators, a revolving restaurant, it's beautiful up there.
Official CN Tower website - http://www.cntower.ca/Intro.html
Underneath downtown Toronto is another fascinating place, the Toronto PATH:
To borrow a quote about it:
"According to Guinness World Records, PATH is the largest underground shopping complex with 28 km (17 miles) of shopping arcades. It has 371,600 sq. metres (4 million sq. ft) of retail space. The approximate 1,200 shops and services employ about 5,000 people."
The PATH is a network of pedestrian tunnels linking various downtown locations & public transit.
It's heated in winter and air conditioned and it's like being in a giant shopping mall.
It's also handy for getting around downtown when it's too hot/cold/stormy outside.
Speaking of shopping, the downtown Eaton Centre mall's glass-ceiling is a tourist attraction.
Then there's places like Toronto's castle, Casa Loma.
And if you're into arts and culture there's the Royal Ontario Museum and Art Gallery of Ontario.
More touristy type stuff here: http://www.seetorontonow.com/
The TTC public transit system's easy to use with lots of ways of getting around:
-Buses, streetcars, subway, LRT trains, harbour ferries out to the Toronto Islands...
Restaurants. There's over ten thousand of those. So you won't starve, that's for sure.
Toronto's more ethnically diverse than New York City so Toronto cuisine is world cuisine.
Different people have different tastes, so here's a handy website to what's available:
Link - http://www.dine.to/
If you're legal drinking age for Ontario (19 or older) the club scene's awesome.
Toronto's a city that loves to party:
Link - http://www.hotoronto.com/hotspots.htm
Toronto's Entertainment District becomes the Club District at night:
Link - http://www.tobars.com/toronto-club-district-map.php
You'll find places like The Guvernment, North America's biggest dance club.
The Guv holds a maximum of 10 thousand people and it's amazing.
Link - http://theguvernment.com/
Plus the top 10 for 'normal size' clubs: http://www.clubcrawlers.com/top10
My fave hotel in Toronto is One King West.
Awesome views like this:
Link - http://www.youtube.com/watch?v=B-wYtkGaBSs
And the suites have everything a busy traveller could want or need:
Link - http://www.onekingwest.com/suites/premium/
Hope that helps and that you guys have a great time in Toronto!