[Christien]

An iphone disables data roaming by default, so if you don't want the additional charges, you don't have to do anything. I looked into roaming plans and costs for a trip to Florida, and it was disgustingly expensive. I would imagine Europe would be twice as much. Though US-based cell providers are much more reasonable in price than Canadian ones, so it may be decently priced. You'll have to go into the settings and enable data roaming.

We're going to spain this summer, and our travel agent recommended buying a SIM card once there. She said that's the most cost effective way of using voice or data. Though if the hotel has wifi, and we are ok with containing data/phone usage to the hotel room, then that's probably the cheapest way to go.