You definitely get a better rate using your bank debit card but be sure to use it only in a secure area like a bank. For travellers cheques, the best exchange rate I found was, surprisingly, in the airport concourse, North side closest to the main street exit. The bank across from there has the same rate but when you get through the line, the teller will tell you that the rate is for cash. A lower rate applies for T.Cheques.