Do not bother exachanging USD into Euro's. No matter where you do it at, you will be raped. Especially do not EVER exchange at an airport or any currency exchange place. You will get the worst raping there!
I have traveled to many many places throughout the world, including all over Europe, so I feel I have a good grasp on things when it comes to smart traveling. I suggest that you just use your ATM card over there as normal in their ATM machines. The conversion is done between the USD in your account and whatever the world exchange rate for is that day between the two monies, and then the local currency is dispensed at the machine. No fees. Well, technically there are international transaction fees, but we are talking literally pennies. This also eliminates the need for carrying large sums of money on you during the first part of the trip which can either be lost or stolen in some cases. Just make sure to call your bank and notify them of when and where you are going so that they don't block any transactions while you are overseas due to assuming that your card info has been stolen.