My sister and her family are in Toronto this week for vacation. Her kids have never seen it snow or experienced really cold weather (born, raised and still live in Florida) that’s why they’re in Canada. Any suggestions as to where they should go? Any other ideas about what to see, do or eat? They have an open itinerary and are open to suggestions.
It’ll be crowded for many things since school’s out but here’s a few for starters:
Ontario Science Centre
Casa Loma (castle-like historical mansion)
Toronto Zoo (open even in winter, but don’t go if it’s really cold, IMHO)
CN Tower
Toronto Eaton Centre (shopping)
Toronto Harbourfront Centre (lots to see and do here)
And, look here (“Toronto.com”) for more ideas.
(BTW, if they haven’t felt the cold before, they’re in for a treat. It’s going to feel like -25 degrees C with the windchill tonight and tomorrow)
The Hockey Hall of Fame
Niagara Falls–it’s amazing in the winter and much less crowded than summer (except for New Year’s Eve…)
Ah, my favorite vacation spot. 
Whenever I go to Toronto I make it a point to go to the Ontario Science Centre like KarlGauss says, and I will not pass up a chance to visit the Royal Ontario Museum. It may be the best museum I’ve ever visited, though I admit I haven’t been to many.
I second most of the recommendations already made and I’d add take a walk through Chinatown on Spadina St.