AM: Watch the changing of guards in Parliament Hill, then tour the parliament hill. Take a walk down the stairs to the back of the cliff, beautiful photo op.
Lunch: Walk over to the Byward Market, many excellent restaurants there.
Afternoon: Taking a stroll along the Rideau Canal, have beavertail at Dows Lake. Take the children to the Museum of Agriculture to pet animals.
Day 2:
AM: Have breakfast at Le Cafe du Musee at Museum of Civilization, you have an unobstructed view of the Parliament Hill. Then watch an Imax movie or even a double feature. Children can play in the Children's Museum
Lunch/Early afternoon: Pack a sandwitch and bring it with you to Gatineau Park, have a pic-nic in Mackenzie King Estate or at Champlain Lookout, then take a hike around Pink Lake
Late Afternoon: Take an Ottawa River boat cruise, departing from the Rideau Canal locks by Chateau Laurier
Day 3:
You can either visit the National Art Gallery and do some shopping at the Rideau Center, or
make a day trip to Perth, just relax in the vast green space in Stewart Park. The Perth Wildlife Reserve and Purdon Conservation Area are within close proximity to Perth as well.