We just did this last fall while on our 3 week honeymoon to Italy, staying in Venice, Amalfi, and Montepulciano for a week each.
We bought an electronics transformer from Amazon, and most cheap chargers will tell you they are not to be used for electronic devices, so I'd look for one that is compatible. Look on Craigslist as well for people who are selling theirs cheap. Ours had the standard European package where it'd mate to anyone's wall outlets using adapters. I also bought a power 'strip' that has sine wave and surge protection with two 110v outlets and 2 USB outlets on it, which I'd use to charge multiple items and for a little extra electronics protection.
I also bought this
rechargeable battery for $38 (on sale at the North Conway outlet) and used it to charge the two iPhones and Kindle when they'd run down, which it would do for 3-4 days before it needed recharging. The trains between places can take a long time, I think our longest trip was 8 hours, and it was nice having the battery power to stay in touch and entertained.
I have an iPhone 4S and did not want to add an extravagant international plan, so I used an old iPhone 3GS I replaced years ago. I jailbroke it to unlock it from AT&T and when we got to Italy I bought a SIM card for 35£ and international calling for an additional 15£ (about $65 total). They have European SIM cards available as well, but we were mostly staying in Italy so I didn't need to spend the extra $$$. This gave us unlimited data and 200 minutes of international calling, including our own phone number in case people had to call us. With the jailbreak I was able to upload MiWi to the 3GS, enabling me to tether the 4S to it (turning it into a wireless router that used the cell towers), which was much faster than using the 3GS by itself. Unfortunately, the Kindle will not tether to an iPhone so my wife was SOL. From this setup I was able to update websites, send and receive e-mails and photos, and do pretty much anything else I wanted. Yes, most of Europe has wifi, but it's often locked, and most restaurants we encountered wouldn't give out the password unless you were buying a meal. This precluded the notion of occupying real estate for paying customers, and even then it's not like you could just sit there and do things online for a long time. Therefore I could sit on the deck, beach, or train and do anything I wanted for as long as I wanted and the wireless bluetooth keyboard really came in handy for typing long messages.
I set this up mainly as a way to stay in touch with people at home and was glad I did because my wife's mother passed away unexpectedly so we had to cut our trip short. We had just moved from Amalfi to Montepulciano and were able to keep in contact the whole time about her condition. We finally had to make an emergency trip home when things worsened.
In addition to being able to keep in touch, the iPhone was really handy for finding our way around Venice (it's easy to get lost), look up bus/train/water taxi schedules, book excursions online (like to Pompeii, Vesuvius, and the Island of Capri), and especially act as a translator since we speak very broken and rudimentary Italian (thankfully French is close so I was able to muddle through some of it). It was especially nice to know not to order the cavallo dish, which is made with horse meat.
I know it's more information than you asked about, but I thought I'd throw a little more in there for consideration.
