Having been there 40 plus times ...I say: don't use an ATM, I have encountered a $6 fee plus a fee on my bank account back home! Yes two fees each transaction! If you're doing $100 a day it really adds up. The bankmart that newb mentioned is good and there is the other kind of hidden one down town and there is on on the beach road( Makes no sense but NO Signs out front) it's in front of Bourban Beach and across from Times Square. We stay at Bar-B-Bar so it;s out our front door, cash $100 or $200 a day and you're golden no banks on Sundays or holidays. Use the cambio in the airport for a starting $100 or $200.