Barcelona to Italy in July/Aug with 2 Teens - where to travel?

Based on what you said you want to see (Cinque Terre, Rome and Pisa) and 10 nights this looks possible Italy itinerary:
Take a direct flight to Rome (stay 4 or 5 nights maybe daytrip to visit Orvieto)
take train from Rome to La Spezia or Riomaggiore to explore Cinque Terre ( the5 towns) stay 4 or 5 nights include a day trip to Pisa fly out of Pisa nonstop to Barcelona.

(I did not include Florence because it is inconvenient to Cinque Terre But you maybe able to do a day trip).

We are traveling Barcelona, to Rome in July with two teens, looking forward to reading replies. I did just see very cheap tickets from the West Coast to Barcelona on new airline "Level", it is a branch of British Airways.

Dubrowa, I do not know where you live, which might be a factor here. It can be quite hot in Italy in mid-summer, and I even had hot weather in Barcelona in early August 2016. Will you and your children be OK (if it plays out that way) being out in high heat during much of the day for a nearly month-long vacation? I can tell you that it is draining, because you'll find that little cafes and shops in Europe are not necessarily air conditioned (nor are some museums), so it can be difficult to find a place to take a mid-day break unless you go back to your hotel or are at the beach.

I'd suggest building in some time in a place where you can be just about assured of escaping the heat. The Dolomites in Italy (up near the Austrian border) work well for that if you stay in one of the mountain villages. There's good transportation from the (hot) valley towns served by railroad up into the mountains via bus, and there are mountain lifts to take you higher. There are wonder walks from nearly totally flat to more challenging. Bonus: Bolzano, one of the best places to hop off the train and get a bus up into the Dolomites, has a museum housing the Iceman.

In deciding where you might stay for a beach break, which sounds like a great idea since you're traveling with teenagers, you should Google for pictures of the local beaches in the summer. Many European beaches are rocky rather than sandy; I'd consider them uncomfortable for a multi-day visit (though I'm not a beach person at all...). Also, the accessible ones tend to be far more crowded than some Americans are used to. Good beaches in the Cinque Terre are limited, and the towns themselves often get really blitzed during high season due partly to heavy daytime cruise traffic from mega-ships. Do some research on scheduled port calls to see what you're in for, before planning to spend multiple days there.

CruiseTT schedule for port of Livorno (click on appropriate months)
CruiseTT schedule for port of LaSpezia (ditto)

Thanks for your reply, acraven. We live in the SF Bay Area - very mild, and the kids are not acclimated to that much heat - very good point. I wonder if I should head in another direction completely? Any thoughts? I so want to visit Italy, but don't want to make my kids hate it, just b/c of heat. Other thoughts for that general region are most welcome.

I adore Italy, but for Bay Area residents I think the mid-summer weather is risky unless you are planned to wing the vacation (not so easy as a group of 3) and potentially spend the whole Italian segment in the northern mountains--which I don't think is what most folks have in mid for their first trip to Italy!

Although Barcelona can get up into the 80s (and sometimes has enough humidity to make it feel warmer), the Pyrenees are not all that far away, nor is the Basque Country. The latter's probably easier to manage without a car; the Pyrenees might be a possibility via rental car after your husband joins you.

Pretty much the entire northern coast of Spain east of Galicia trends much cooler (and damper) in the summer than the rest of the country. I think your Spanish-studying children might get a kick out of all the Basque-language signage, too.

Another possibility is the Picos de Europa area that straddles Cantabria and Asturias--probably the most dramatic mountain scenery in Spain. It's really pretty, full of mountains and gorges. It's my impression that (in addition to the obvious walking) there are some active-sport opportunities in the area in the summer, though I haven't researched them. I'm not sure it will be so easy to figure out teenager-friendly spots in the Basque Country or the Pyrenees, though the towns are picturesque and the countryside is lovely (scenery...teenagers...scenery...teenagers; I have some doubts, just remembering my attitude toward car trips in the NC mountains) . San Sebastian has a pretty incredible beach, though, and there are nearby former fishing villages with beach access as well. Understand that you can't count on warmish, sunny beach weather every day, though (which is why I'm confident in saying you wouldn't run into an extended hot period in this area).

Activities appealing to teenagers will probably be substantially easier to find in Barcelona, and I assume Montserrat will be pleasant, weather-wise. It's not an easy decision.

Pick up a comprehensive guidebook (doesn't have to be current) from your library or bookstore and see what you think about branching out in northern Spain.

Edited to add: If you and your children haven't seen the Rick Steves videos, you can watch them on this site. If everyone is excited about the chosen destinations, they may be less inclined to complain about the inevitable days with less-than-ideal weather.

I should perhaps have mentioned earlier that not only do I live in the swamp that is Washington DC, but I grew up in North Carolina and Florida. When I say that heat is likely to be an issue, I am not overstating the case.

From BCN you can pretty much fly anywhere in Italy with Vurling. BCN is Vueling Airline hub (Vueling, Iberia, British, Level) are all part of IAG group. That time of the year it's hot, but not any hotter than inland in the East Bay (Tracy or Antioch)

What in Italy interests the kids? Would they prefer spending time in the cities or by a lake? Canals of Venice, art in Florence or ruins of Rome? With the exception of the mountains, it will be hot and probably humid. I am not a fan of heat and humidity (live in VT where 70 with a breeze is perfect) but I have been in Italy in Sept when I thought the heat/humidity was tolerable because I was in Italy!
Options I would consider:
1. Venice then Lake Garda or the Dolomites
2. Florence then the CT
3. Rome then Sorrento/Amalfi coast

My preference would be 1 or 2, but that's me. All easily done once it Italy by train. Multiple airports back to BCN to choose from depending on where you decide to go.