Thanks so much for the adviceEvery bank and Hotel will give you different rate of Exchange, ask the hotel what rate of exchange they will give you; go with the one that gives you the best rate.
Go with reputable institutions. If you bring the money in Euro and exchange it at Vimenca or Western Union they give you relatively good rate and they have an excellent international reputation. Usually you can tell them if they can give you a better rate for larger amounts, keep the receipt and you can return the pesos if you do not need it at the end of the trip. The hotel is the largest expense ask if they can give you a better rate.