Waze and driving in Italy

Give or take 1Mb for each hour of driving. But it varies depending if it's same route or new route, 3D vs 2D, whether you preplan the route while connected to a wifi at home/hotel.

But overall I don't think the nav systems use a lot of data compared to surfing the net (will you be doing that also with your phone?).

You can also purchase a local SIM card with a data plan, if your phone is unlocked. This is what I usually get. It's a plan designed for foreign visitors. 30€ for one month for 2Gb data+300 outgoing voice min+300 outgoing texts worldwide (Incoming calls and texts are always free to the receiver).
http://www.vodafone.it/portal/Privati/Tariffe-e-Prodotti/Tariffe/Estero/Vodafone-Holiday-English

30E ! that sounds like an awesome deal. I wonder if my Samsung 6 is unlocked (Verizon) how do I know if it is or not ?

but then how will my family text to my "now European" phone, obviously it will have Italian tel # and they need to call and text to that one ... right ?

kari ..all Verizon LTE phones are unlocked. Yes, they will have to call/text to that number

Waze worked amazingly for Italy for me, just as good as in the USA. Even alerts you to speed traps/cameras!!! Only thing it does not do is advise about ZTL zones.

You should be able to go to a store with your phone or even probably call Verizon for them to tell you if your phone is unlocked or not. If it is new it is unlocked since they did away with the multi year contracts.
Instead of going that route, I rented a wifi hotspot from Expresso Wifi and it was fantastic and still fairly low cost. Never used one bit of data from my phone and had a good signal everywhere for Waze navigating plus my daughter to watch YouTube videos while I drove to make things easier.
We made calls back home via Facetime which was nice and also used no data.

wow ! "Expresso Wifi " Now that sounds like an awesome idea !
Where did you get that from ? Airport ? How much was it ?
Im going to start searching for it right now

Expresso wi-fi costs €5/day (or did when I checked). I'm going to be in Italy for a month and so would have cost me a lot, but if you only need it for a week it might end up costing about the same as the 30-day sim card deals.

If you buy the Vodafone Holiday deal you will have an Italian telephone number. Your family will need to contact you at that number. To call an Italian cell phone number it costs about 30-35 US cents a minute (depending on long distance service). Texting an Italian number is about 50 US cents with most American mobile phone providers. The cheapest option is for you to contact your family in the US rather than your family to contact you at your Italian number. Remember that Vodafone Holiday comes with 300 minutes and 300 texts worldwide, which you can use to call or text your family back in the US. If your family wants to contact you, they can send you a text for 50 cents and then you call them back with your Italian phone.

I used Expressowifi this summer and it worked wonderfully. Expressowifi was the best priced and their service was incredible. You can take the device at the airport or your hotel and you turn it back in the same way. Love it!!!

Waze worked amazingly for Italy for me, just as good as in the USA. Even alerts you to speed traps/cameras!!! Only thing it does not do is advise about ZTL zones.
Yep. Works great for speeding, but all parking and routing should be compared against a ZTL map of the city you're going to. Towns as small as Serralunga d'Alba can have ZTLs.

Have the folks at home take a tech step back. They can always send an email at no cost. Also, TIM is another cell phone provider with a tourist plan that costs the same as Vodafone. Biggest difference is you get 4 gigs of data and no texts. If you text, each one costs .15€. Here's a link for more info. If you're flying into FCO, there's a TIM store at the airport.