From what I have read - a credit card company charges anywhere from 1.8-3% on top of the daily exchange rate.
A bank will charge anywhere from 2-4% over the daily exchange rate as a fee (as is stated on the Bank of Canada website).
For example - today the market exchange rate is around .09628 (so far) but my bank is around .94 - the 2% discrepency covers all fees and any changes in the exchange rate throughout the day.
If you are buying traveller's cheques, you may get them for free if it is part of your bankcard/creditcard agreement. Otherwise you will pay a fee. My bank charges 1% (so $1000 would cost me $10) - if I had a platinum Visa card the travellers cheques would be free.
I checked out the BMO and their US accounts, and found that unless I have a minimum of $1000 US in my account at all times then I would have to pay a monthly fee ($4-$14/month for so many transacations) and $25 per year for the US Mastercard with BMO. Many BMO, TD, RBC customers stated that when the exchange rate was good they would transfer money from their Canadian accounts to their US accounts and then pay their US Mastercard or Visa, but that "good rate" is still a bank rate (market plus 1-2% for fees) - maybe they get a better rate than me but it's still not market rate (banks do nothing for free!). For occasional border travellers like myself, the math just doesn't work.
Personally, I will probably buy the travellers cheques for the following reasons....
1. They can be used throughout the parks or cashed in at a Disney resort
2. I will always know exactly how much money I have to spend (you can easily lose track when everything is being charged to a card)
3. I won't have to worry about the fluctuating market (when you use your ATM or Credit card everyday the exchange rate changes in accordance with the market) and every time you use your cards there are the fees to consider
4. If I am going somewhere on or off property that I am uncertain will take my Canadian debit or credit card (like some gas stations), I will just cash in a couple of traveller's cheques at the front desk before I leave.
Just my 2 cents

Please correct me if I have gotten anything wrong
