Do not change money at the airport! You will get a dreadful exchange rate. I tried to change £1000 in to US$ and was offered US$976 in Madrid airport last year.

For convenience sakes, I always take 200 euros from home so I don't have to bother looking for machines as soon as I step off the plane. The extra cost is worth the practicality of it. When I run out, I start using the atm's....