I will personally welcome you right now as I live approximately 10 minutes away from the congress site. Will you be arriving before the actual event dates? Or do you start from the congress?
Any time that I have a choice between bus and train, I would choose the train. I would suggest starting from Montreal or Quebec prior to coming to Toronto/Mississauga for the congress. Each city is worthy of at least a couple of days. I would also give Toronto at least two or three days beyond the actual congress. You should fit in Niagara Falls (seven wonders of the world and all).
Fly to Calgary. Absolutely take the train between Calgary and the west coast. If you can, stop and spend a day in Banff enroute.
I would give 50% of your time to Quebec and Ontario and 50% to the west (Calgary, the rocky mountains, Vancouver and Victoria.
The real question is what do you want from your trip? Some want shopping, others history, yet others desire theatre or concerts or photographic opportunities.
Will you have dogs with you?
We are a big country and not inexpensive. But--- I am a totally proud Canadian and will help you any way I can
Train travel between cities is always with ViaRail (
www.viarail.ca) and typically the best air fares from Ontario to the west are with WestJet.