Sounds like an ambitious itinerary! Your timelines don't strike me as unrealistic though... a week in Calgary, a week getting to Vancouver, half a week in Vancouver, half a week in Toronto/Niagara Falls.

The only suggestion I'd make is at the back end of your trip... I'd make it a Toronto stay and then do Niagara Falls as a long-ish day trip where you set out early in the morning and come back late in the evening. Unless there is something particular you want to see that will take longer, I think a day trip to the Falls and the Niagara on the Lake area would probably suffice if you only have 3 full days in the region.

Bon voyage!!