I think the 3 days for 9 euros may be the only option you have. SFR has a 250MB plan for 1 month but you may also need a French bank account for that one. I was there in July and purchased the 29.99 euro unlimited plan for 1 month (I have a French bank account and address) and it worked beautifully other than problems with the purchase itself. None of the staff had seen an iPad before but had the proper micro sim for it available. They had not idea how to do the sale and gave the wrong instructions for the setup. I assume these problems will go away with time plus I was in the southwest. I have read that the problems were similar in Paris, though.
They require the French bank account because they will draw the payments from your account rather than from the credit card. Which means you need to bring a RIB form (RELEVÉ D'IDENTITÉ BANCAIRE) and identity card with you so they can process the payment. They told me that canceling after the first month would be just an easy phone call. Far from it. We called, a friend there called and visited two SFR branches, we sent a registered letter, then called again, and finally it was canceled but not before they had collected a second payment. They just told me they would be refunding most of it.
We were also in Spain but did not use the French SFR card there as the charges were exorbitant. We were not able to find an Orange or Vodafone branch in the Valencia/Alicante area that had the sim for the iPad available.
Trust me that opening a French bank account from the US is almost impossible. In most cases, they require utility bills from your French address, copy of your passport, tax forms from your US taxes, utility bills from your US address, etc. It is less about terrorism and more about money laundering and tax avoidance.