Our main suggestion is to take the opportunity to visit the St. Jacobs Farmer's Market at the north end of Waterloo.

There's also the Kitchener Farmer's Market, though we've heard it's not as good as the St. Jacob's one. On the other hand, it is right across the road from the Sheraton Four Points where our reception will be.

SportsWorld and Bingemans are good places to keep kids busy

Angie's Kitchen: We're actually hoping to meet up with people the morning (afternoon?) after the wedding for breakfast/brunch here.

Not quite in Waterloo, but the Wings of Paradise Butterfly Conservatory is apparently interesting

There's other stuff too, and instead of going into too much detail, here's a couple of links to other websites. Unfortunately, I couldn't find any extraordinary sites. These appear to only cover attractions/places that were willing to pay to get listed... Kitchener Waterloo Tourism and Regional Municipality of Waterloo