Wifi Availability (and rental)

Hard to ever make a blanket statement about a country.
Sounds like you want to know outside of your hotels is there free wifi hotspots in towns/cities?
This will be very town/city dependent, same as it would be in the US.

If I were in Yellowstone National Park in the United States I would struggle to get a cell phone signal of any kind let alone have a wifi hotspot within many, many miles.
I would give your itinerary for a more helpful answer. Just like in the US some areas will have them others will not.

This article may be helpful for you:
http://www.apathtolunch.com/2014/05/free-public-wifi-in-italy.html

It all depends how perfect you need the plan to be.
if it needs to be fool proof and is a very big deal, no it is not a great plan, for that I would rent 2 wifi hotspots if you are very worried about becoming separated or a hotspot for each phone user although likely a waste of money.
SIM cards for their phones are likely cheaper but more of a hassle.

Otherwise most families surviving for decades without each child having a cell phone and as you mentioned your hotel or where you are staying has wifi so that can be used to connect back home without adding more expenses.
Don't want too get all 19th century on you though, I plan on renting a wifi hotspot for our trip, plan on using my-webspot.com for the service personally mainly for the convenience of being able to use apps for our cell phones and so my daughter can be entertained on car rides.

In hotels wifi is often worse than in the US in Italy since many of the buildings are older and have thicker walls it is more commonly the case that the lobby may have great wifi but up on a certain floor they might not get the signal.
This happens in the US as well and is very hotel and room specific. In Italy as in the US if you tell the hotel wifi signal is important they hopefully can put you in a room with a good signal, they should know which areas are better than others.

I have no idea how available wifi is where you are from, nor where you are going in Italy.

I never have much trouble at my hotel or when out and about. More detail from you will yield a better response.

Why do you need a portable wifi, and all its costs and inconvenience?

Facetime works fine, as does WhatsApp and so does Skype.

Depending on where you are from, there is likely to be a multi hour time difference so that may well be the biggest problem. Scheduling calls by email works well.

We have found it easier to just check in by email, since the time zones aren't an issue with that. But it is easy to use wifi for texting and calling apps, and you will find it widely available. As for the issue of getting separated, how realistic is this? Just set a meeting point if you are going different directions, like we did in the olden days of 1976. Make a plan for what happens if someone is actually separated, say, getting the metro. Whoever made the train gets off at the next station and waits for the others to catch up.

Your hotel will have wifi, sometimes included and sometimes for an extra per-day fee. And as noted, it is not uncommon to need to use the wifi in the lobby for decent connections. Depends entirely on the hotel and their wifi network setup. Connections can also be slow if there is a lot of traffic on the network. But in general, this works very well for emailing, texting and sometimes for Facetime or Skype.

As for connections while out and about, many restaruants/cafes will have wifi and it's not uncommon for people to buy a soda at McDonalds to get on their network. Public wifi can be very hit or miss and I wouldn't depend on it for emergencies.

As someone else noted, have an emergency plan for cases where you might get separated. Not sure how old the kids are, but if old enough to be ok on their own some, make sure they have the hotel's business card on them that can be used for someone to help them find their way back to the hotel. In places like museums or sites, agree on a meeting place like the entry or a major element.

I would also recommend having one of the phones with an international calling plan. That can be done various ways, including your own service provider or a 3rd party. I wouldn't do it for all phones as it is expensive, but make one phone the primary contact in case anyone needs to reach you in an emergency. All the kids should have that number on them and of course families back home.

Also, be sure that data is turned off on all phones all the time or expect some very hefty bills on your return. Even if turned on for short times, your phone will try and "catch up" with data since it's last connection and you could still wind up with large data transfers. Be sure the kids understand the reasoning for this so they don't turn it on while bored or desperate to text their friends or some such thing.

My experience with Venice, Florence and Rome is that each city (as well as Vicenza and Padua) has both municipal and commercial WIFI hot-spots. I saw plenty of TIM, Tre and WIND WIFI hot spots in the various cities... Now, here's the other shoe. I've heard and read that "anonymous" WIFI connections are not allowed under Italian law (I don't vouch for the validity of this statement, it's just what I've read and heard) so in order to connect, you must create accounts and log in. For example, in Venice, 30 minutes at day was free upon logging in but after that there was a nominal charge. In Vicenza, you had to SMS text a number (advertised on street signs), and an access code was returned via SMS text. On the trains (Trenitalia), WIFI was complimentary if you supplied your local phone number.

So, although there appeared to be a lot of free (or low cost) municipal WIFI, you often needed a local phone in order to access it. The good news is, your iPhones are probably factory unlocked and capable of using a local pay-as-you-go GSM SIM card. The plans I looked at last year were euro25-30 for several hundred minutes (~5c a minute to USA), several hundred texts and 1 or 2 GB of data. This is a small price to pay in order to stay in touch when you keep in mind that you don't have to get SIMs for ALL of the devices.

An alternative is something like ExpressoWiFi which was reviewed in the RS Technology Tips forum a while back.

I would, however, stay away from the other "tourist oriented" cellular brands as their services seem exorbitantly expensive.

Thank you all for your responses. I was remiss in mentioning our travel cities which each of you pointed out - sorry...we are traveling to Florence and Rome. While we always have a plan to meet up if we are separated, I think that having the information regarding wifi and contact as a backup is a helpful way to ease my family's mind and fear about being in a foreign country for the first time and losing Mom/Dad/Spouse.

Also, the wifi is important as the children going with us are in their early teens.

Thanks.

Who is your current US carrier? Before doing anything else, check their terms for use in Italy. For instance, if you have a T-Mobile Simple Choice Plan, you get free unlimited texts, free unlimited internet (officially limited to 2G speeds, but many report getting faster speeds much of the time), and calls for $0.20 per minute (to or from anywhere). I believe Sprint now has a similar deal. AT&T and Verizon have pricier plans, but they may work for you (if you can get the kids to limit their Internt time to using Wi-Fi at the hotel).

If you really want or need Internet at all times and don't have a US plan that gives you this, you'll want a Wi-Fi hotspot.

How old are the children?

Both Rome and Florence have multiple public hotspots, some provided by bars/cafe's etc., and also (in Florence at least) by the City of Florence. However you need to log in first and accept the terms, etc. Also the city provided hotspots are not necessarily in every corner.

For emergencies, if you all have phones, you can actually call one another. Even AT&T, which is very expensive, charges $1.29 a min max (or 50 cents per text). Not cheap, but in an emergency you can certainly afford those amounts.

If your children intend to surf the net constantly while out and about, I can tell you that international data roaming alone could kill your budget. Some providers offer decent international plans (like T-mobile) that are not expensive, others, like AT&T, want $120 for 500 Mb, which is a rip-off. There is also the possibility of getting a local SIM card with Vodafone (Holiday plan, designed for tourists, is €30 and included 300 int'l minutes, 300 int'l texts, and 2Gb of data), however with a local SIM card your phone will have an Italian telephone number.