Ottawa is a lovely place to visit for a weekend. I've made 3 separate trips in the past 6 or 7 years. I've been twice in May and once in November. I can fully recommend the Canadian War Museum, Air and Space Museum, National Gallery of Canada, and Ottawa Senators NHL Hockey. Walking along the Ottawa River and along the Rideau Canal is lovely too.

I can also fully recommend Quebec City as well. Lovely shops, great restaurants, very scenic. Old town is very easy to walk around.