A possible solution for mobile data in France?
 

iPhonetrip.com has gotten a couple of good reviews on Flyertalk forums from a couple of members. It runs about $15 a day, which is pricey but supposedly "unlimited" data. If you can get a couple of Mbps downloads and use it for laptop and smartphone, it might be viable.

tepwireless seems to promise unlimited data as well.

Actually, these services make more sense if you're visiting more than one country. If you're only visiting Italy, then you get a SIM from an Italian carrier. But if you're visiting Italy and France on the same trip, you might be getting a "universal" SIM for $15 a day.

Their definition of 'unlimited' (it never actually is unlimited) is 7GB per week, as a simple google search points out. Still seems to be quite a good deal though!