Just hit the ATM when you land or are in the city. They are everywhere in the city center. ATMs will give you the best rate without "commission" that currency exchange places in the airport will charge. There are also tons of currency exchange windows in the city. Even though they claim "no commission", their rates will be bad.

Don't know about BoA, but Lasalle does not charge me fees for using other ATMs. I have also never had an ATM in Europe charge a terminal fee. The exchange rates I get are within a penny or two of the daily published exchange rates. Even if they do hit you for a dollar or two per transaction, it will be cheaper than commissions and bad exchange rates.

If you end up with extra Czech currency and need to change it back to USD, you will get hit again on the exchange. Just take what you need from the ATM.

One other point - make sure you have funds in you CHECKING account. I can access both my checking and savings from my ATM card in the US, but am never give the option in Europe. It comes directly from checking.