Best exchange rate for our smaller amounts of US$ to C$'s or vice versa has not been the banks but the Exchange currency desk in our local mall believe it or not. On just a couple hundred UK pounds exchanged to Can dollars we ended up C$60 better off so ...........
Check credit card fees for using out of country as most do charge a premium.
For larger (house sales or similar) money exchanges we use a company like MoneyCorp or similar that doesn't have the spreads and extra fees our banks tend to charge us.
Also Alberta is the only province within Canada that has ZERO PST/HST on goods, and generally for the most part has the cheaper gasoline has been our experience. As stated before, BC tends to a lot higher priced by comparison to our province, to the tune of we say "BC stands for Bring Cash". Gorgeous province to visit but sure is expensive compared to many others we've travelled in.
And yes, generally speaking almost everything (California type states aside), is generally cheaper to buy in the US than Canada even with a 25% exchange rate premium considered.
Enjoy your trip to our beautiful country and do take time to smell the roses as you go!
FTW