the rideau waterfall is worth a look, its where the rideau river empties into the ottawa river, its very close to the centre of town.
https://www.flickr.com/photos/150942182@N05/shares/v9N9S1
There will be nhl hockey at canadian tire centre, (plenty buses go out there)
Canadian football at td place, (walkable in 15 mins from the centre of town)
There’s also the rideau canal, the oldest functional canal system in the world and a unesco world heritage site, however atm its drained as they prepare for winter operations (in winter it becomes the largest skating rink in the world)
Byward market a great area for food, there’s all sorts of restaurants, and our experience is they’re not that expensive.
Last time we were there we drove out to wakefield in quebec, a little village which was very picturesque, id imagine it could be pretty busy in summer like.
I love ottawa, can you tell?