Knowing absolutely nothing about your or your family it is impossible to predict what you might or might not like. Check the Toronto tourism bureau http://www1.toronto.ca/wps/portal/toronto/portal?vgnextoid=6bf6d1e80065c210VgnVCM10000067d60f89RCRD and other similar sources to get started; then you can pose questions that will motivate useful answers.
That's harsh (but right). To soften my tone, here is a suggestion for an offbeat seasonal attraction. Every year Ross Petty, local impresario, stages a lavish English-style pantomime. This is not Marcel Marceau but rather a rowdy musical revue with funny business and men in skirts. Petty is so well connected (his wife is a famous ballerina and artistic director of the National Ballet) that surprise appearances can happen. Theme this year: Snow White. You can bet it will be 'Dopey'. Details at http://www.rosspetty.com/ As a bonus, the Elgin Theatre is very handsome and historically significant.
The Wizard of Oz, with a Toronto cast, will also be in residence at one of the Mirvish theatres http://mirvish.com/shows/thewizardofoz The Mirvish production of War Horse may still be running, too, if your family is a little more adult.

How old are the kids? Are they picky eaters? Will they eat 'adult' food? And about what price range are you looking for?

A decent chain is Milestone's and there's one quite near the CN Tower, just north of King on John Street (or maybe it's Duncan -- check their website). There's a big strip of restaurants on King just across from the TIFF Bell Lightbox and a good family-style Italian place called Il Fornello across from Roy Thompson Hall.

Check websites for Roy Thompson Hall, Massey Hall and Mirvish Productions to see what might be on. Also, kids tend to like the Hockey Hall of Fame.

They might enjoy the St. Lawrence Market for lunch on Saturday. It's always lively and there are fun places to eat both upstairs and down. And it's a nice area to walk around in after lunch as well.