Ontario has a lot to offer, even besides Niagara Falls. People who prefer cities can always find something to do in art-filled Toronto, which always strikes me with its cleanliness (I'm accustomed to NYC.) There are adventurous restaurants, lots of events, and public transit that makes it easy to visit if you're staying in a nearby suburb (though I can't speak to the prices, as it's been a while since I've been there.)

There are forests and mountains to explore for outdoorsy types. I used to go camping up in Killarney, north of the Georgian Bay. There are crystal-clear lakes and pink mountains out there that provide incredible views. Algonquin National Park is another great option for campers and outdoorsy types.

I wish someday to visit Ontario again. I have a lot of good memories from that place.