The Toronto Christmas Market is suppose to be pretty cool.
Toronto Christmas Market* |* Rediscover the Magic & Romance of Christmas
Also check out Toronot.com .. there are lots of theatre shows and concerts with holiday themes during that time frame. Nathan Phillips Square usually have ice skaing and other stuff going on around that time. Most major malls will be back and deck with holiday decor to the max.
Just in case you plan on doing any shopping the week before Christmas pre-boxing day deals start showing up all over the place especially major malls as the fight to get more sales from last minute shoppers. St. Lawerence Market and Kensington Market are also cool places to check out around this time of year. Many City of Toronto Hisortical Sites have holliday event (note likely catered to your age, but you never know).