I think my favourite spot was along the boardwalk that stretches the river bank of the entire city. It was so full of people out enjoying the weather, and there was this section where there were cold pools. Kids were swimming, and adults were sitting and dunking their feet. It was so hot out, the pool was a perfect antidote.
We also went to a free show one evening (there is a free Cirque de Soleil, but it doesn't show two nights a week, when we were there!), a huge projection movie against the sides of grain silos across the water.
If anyone is looking for vacation destinations, Quebec is lovely. So much cleaner and cuter than Montreal! (I'm still glad I live in Montreal, I love how close everything awesome is, I love all the people, I love the grungy energy)