CN Tower is amazing way to see Toronto. It's a gimmicky type thing but I love it none the less. Every tourist and resident should go to the top to see the beauty of Toronto, water, city, land. It's a shame that I only got to go in the winter as I'm sure it's much more beautiful in the 3 other seasons!
Go to the Aquarium too if you're here. Even though it's Ripley's attraction, it's truly beautiful, well thought out, and inspiring.