If you’re in eastern Canada check out this:
Parliament hill is nice if you’re into history (check it out anyway if you’re not, Ottawa is a beautiful city).
Quebec city is absolutely stunning, beautiful area. There was a whale watching tour I once went on from that area that was pretty interesting, though we were on the boat for something like 8 hours (though it was a while ago, can’t remember how close we were to the city when we left the dock)
Niagra Falls… Its a tourist trap, really… If you’re going to go there just go and check out the falls then head out… don’t spend all day there. Check out Maid of the Mist, though. The Planet Hollywood and the haunted houses are very expensive… and entirely bla.
Check out Montréal, if you’re into the party scene, its there. If you’re into food, its there. If you’re into history, its there. The language is beautiful but don’t worry, you can survive if you don’t speak it.
Summer activities:
Ottawa, bike up and down the canal.
Sit out in the sun on Parliament hill for a relaxing afternoon.
Check out Canada Day (July 1st) in Ottawa. Lots and lots of fun, I’m there every year.
If you’re into horses check out the events by the RCMP (can’t remember the name of their events)
Tulip festival, Ottawa. I’ve never been there for it but I was once there right after and, while I’m not into flowers, what was left from the event looked pretty cool.
winter activities:
Ottawa, skate up and down the canal. Its awesome, trust me.
Winterlude (combine with the skating)
Montreal has some good skating too.
Skiing, its Canada, after all.
Thats all that comes to mind at the moment. If you’re ever in eastern Canada its worth checking some of those things out.