Make sure your arrive in France with some Euros in your moneybag. You never know when it'll be useful. But one rule is that you will find out at the most inappropriate times…, and the exchange rate at the airport stalls are decidedly not in your favor. If you do decide to change money at the airport, only change enough to get you where you are going. The airport exchange rate is not to your advantage.
On another note (!), please keep in mind that The French do not like to talk about money like Americans do. To the French it is quite rude to discuss how much money you make, or to boast as to how much, or how little, you paid for something. To do so would place you in the ranks of the uncouth and uncivilized.