Personally, I would bring a few Euros, maybe 50 or so, just in case. You never know, the ATMs could be down, or you could have some unexpected problem with your ATM, or you could have difficulty finding the ATM.Though you may be getting a bad exchange rate, you're not really losing that much as long as you don't buy too many euros before the trip. Compared to the total expense of the trip, the money lost on such a small transaction due to an unfavorable exchange rate is such a miniscule part of the total cost of the trip that it's becomes just "noise". Besides, after a long trip, the last thing I want to do is find and fight those ATM machines. I head straight for my hotel.