Outside Ottawa, Ottawa
This place is wonderful. It feels like many little museums all linked together. And you will want to come back again and again because of the many changing exhibitions. And there are also the IMAX films.
The Grand Hall and The First Peoples Hall are on level one, and a must do your first time. The Canadian Postal Museum on level two is good. The Canada Hall on level three is the heart of the permanent displays.
Maxville, Ontario, is close enough to visit on a day-trip from Ottawa. It is home to the largest highland games in North America. These are very impressive and we've been several times. These always take place on the long weekend in August (1st Monday) and people also camp there.
For lovers of museums, especially those which are overwhelming in size which revolve around natural history and local cultures, the Museum of Civilization is definitely a must see.
This is an amazing museum focusing on the history of the people of the world - including amazing exhibits on the history of Canadian people - both the natives and the immigrants, from the Inuit, to the Haida... to the first Viking visits hundreds of years before Jacques Cartier sailed ship.
Trivial info - some Canadians may remember in December of 2004 when USA president George W Bush visited Ottawa, and ate his famous Alberta beef dinner in Gatineau. It was in this museum that the infamous dinner took place.
Just 15 minutes from downtown in Gatineau Park
Drive up to one of the information booths in the park and buy a map. That way you will find the best trails. Dont do the ones off the main road..too crowded and boring. My favs are the Ridge Road and also the one that goes behind Camp Fortune..you get a great view on this trail (after a steep climb) of the valley.
Go camping in Algonquin Park! It's a good 2-3 hour drive north of Ottowa, but it is worth it - beautiful, peaceful, and practically empty. Take a canoe or kayak, or just go for some hikes. There is also a great national park just across the river, outside of Hull. Good day hiking there, too.