Wowzers! Coming from down under!
Yes, you should definitely check out the CN Tower and watch a Jays game. If you are coming with your significant other then you might want to check out Mirvish Production of We Will Rock You, take a walk along Harbourfront and hopefully see a live jazz band, and dine at the 360 restaurant on top of the CN Tower. If your want to party in the Toronto night life, Dance Cave, Mod Club, Phoenix are decent for rock/garage/indie venues, otherwise any club on Richmond plays Top 40.
Check out Kensington Market for an eclectic selection of food, clothes, and anything cool and trendy.
Royal Ontario Museum, Ontario Science Center, and maybe even the Art Gallery of Ontario are also worthy places of viewing.
Oh, and when you're down around the CN Tower/Rogers Center area, check out the Steam Whistle Brewery and get a tour of the place while drinking free samples.
You'll also need to stop by the Silver Snail comic shop on Queen St W.