Family trip to Spain, Italy, Croatia and Poland with children aged 12, 11 and 7.

I know four weeks seems like a long time--and it is, by normal US vacation standards--but the places you are talking about visiting are widely scattered, and each of them is worth a lot more time than a week, even for those who don't have family heritage to explore. You would have to fly from Spain to Italy or Croatia and from one of those to Poland. The trip from Italy to Split or Dubrovnik would also probably entail flying; anything else would take much, much longer. So you'd be dealing with airports 5 times during your 4-week trip. Not relaxing at all.

Even within countries you would have some long travel legs: Barcelona to San Sebastian is at least 5-1/2 hours by train, and Capri will take perhaps 3/4 of a day to reach from Calabria. Taormina might or might not be a trek, depending on where you're headed in Calabria.

Krosno is several hours from Krakow, which I imagine is the airport you'd be using. But you might well have to take a connecting flight to get there, which increases both the travel time and the cost.

There's rail service to all the places you mentioned except Capri, the Croatian islands and Dubrovnik. Buses are used a lot in Croatia. The transportation needed in Calabria will depend on what specific town(s) you want to visit.

Southern Italy and Sicily can be miserably hot in the summer. I don't know that Croatia will be much cooler. Such weather can be hard to handle day after day if you're not in a position to spend a lot of time in the water.

I don't have children, so I can't suggest child-friendly activities except for beaches and pools. I realize you could go to beaches and pools a lot more inexpensively at home, but it's a rare child that doesn't like to play in the water, and I suspect water breaks are a near necessity if you are spending time in such hot places.

If you go to Croatia, I recommend Dubrovnik. Also, Split and neighboring Trogir.

Poland's best city is Krakow. It was not damaged in WWI, while Warsaw was virtually flattened. If you have time, visit Gdansk, Warsaw and Krakow. Not sure I would take small children to Auschwitz Concentration Camp. I think it would be too much for your kids.

Spain, my favorite cities are Seville and Toledo. Honorable mention for Madrid, Barcelona and Granada.

Renting a car in Italy is a bit problematic. Check this website under Italy for issues relating to driving in Italy.

I would just Google, "Europe with Kids" or whatever "country with kids". That way you know your kids interests best and can figure out what they may like and plan accordingly. Your planned countries are spread out so you will be doing a lot of plane travel, especially from Spain to Italy and onto Croatia and then to Poland.

I agree that 4 weeks in 4 countries sounds like a whirlwind, to say nothing of adding kids to the mix (who, in my experience traveling with our 3 kids starting around that age, force you to simplify your itinerary). We have traveled to 3 countries in 5 weeks, one country in 4 weeks, and one country in 3 weeks (Spain), and in the case of Spain, just the northern part due to timing+temps. This is not to say that your plans won't work, it is only tp say that the ideas one has when planning are so exciting and its so hard to "kill your darlings", but that kind of ambition can also be exhausting, and again, esp. with kids.
That said, for a week in Spain, BCN and SS would be enough. There are so many day trips from each . We were in BCN for 4 full days and SS for 2 1/2 and that was great, and we didnt do any day trips (we visited Girona for a separate two days, and areas around SS also separately). For Italy, you have 3 places in mind already, thats plenty. Considering you'll travel at least 1/2 day between each country, and between each locale. I dont have ideas for Croatia or Poland because I haven't yet been.
As for what to do with kids, it is really easy to google "destination X with kids" and get a lot. For bigger cities like BCN there is a book series called "Mission [insert city]" where the kids are secret agents and they have to locate various artifacts throughout the city (they're on Amazon). My kids had fun with these in Paris and Rome. So you could search for Mission Barcelona. Water is always a plus, whether beach or swimming pool, or stream, or sea. European Flights can be cheap on airlines like Ryan or EasyJet, esp if you book early. Carry-on luggage makes things much easier in my experience. Each of my kids has their own backpack and they carry their own stuff (when the youngest was very young we helped by putting some of her stuff in ours). We have found it much cheaper and sometimes easier to rent a car for travel between places. You really have to do the research on a case by case basis. When traveling those 5 weeks we drove from Paris to Nice, then trained through Italy, then flew from Rome to AMS, etc. It just depended on what made the most sense economically (renting a car for the 5 of us is almost always cheaper by a lot but taking the train is so relaxing). Good luck

You are giving each country less than a week ( it will take at minimum 1/2 day to travel from place to place )and want suggestions for more than one destination in each country , and have 3 young kids .Id slow down a wee bit .

As for mode of travel - trains are easiest and most relaxing with kids , but flying is good if train trips are more than 4-5 hours ( I’ve done 6 hours and that was enough for me , probably the last hour I was ready to get off train ) .
Driving adds other costs / toll roads / parking / and gas is way more expensive than Americans think ( reminder, it’s priced per litre not gallon ! ) but driving is nice for exploring countryside .

You will want to avoid renting a car in one country and dropping it in another. The international drop charge is usually really, really high (many hundreds of euros).

I would REALLY reconsider trying to do all of these countries. They are too far-flung. As others have said, a week in each place seems like a long time, but you want to go to several places in each country, and those places aren't necessarily close by or easy to get to. You're going to be moving a lot, and will likely need to visit one, two, or even three different airports to make this work. I understand wanting to cram a lot into a trip - I am guilty of it myself. But especially in the summer, especially with kids, I think you should take a deep breath, remember that you WILL come back, and start, as someone above said, "killing your darlings." Ask yourself - and then let us know, so we can help - What are your Musts on this trip? Is it to visit family/places family lived?

Here are some ideas.
1) THIS SKIPS CROATIA. Fly into Barcelona and stay three-five days. This will give you - and the kids - the chance to recover from jetlag and explore the city. Take a day trip, or even two. Then get on a Disney cruise. Yes, a Disney cruise. You wanted suggestions for things your kids will like? This is it. I haven't done a European cruise, but we did a four-night Bahamas in May 2018 and my kids STILL talk about it. There is a seven-night cruise that leaves Barcelona on June 6 and drops you in "Rome" (Civitavecchia) on June 13. Unfortunately that looks like the only time for that cruise. But now you're on Day 13, say, and you're in Italy. Here's where I am of little help, as I don't know southern Italy at all, and it seems Calabria is a good-sized region. Is there a city/town you'd want to stay in? Is Sicily a priority? Only you can answer that. My suggestion is pick a place, rent a house with a pool, and chill for a week. Take day trips. But don't go moving locations every other day. Now you're on Day 21. Make your way to Naples or some other airport, and fly to Krakow. Don't go to Auschwitz. Do go to the Salt Mines. Rent a car for a day or two and drive to Krosno. It looks like its roughly two hours from Krakow. You could do a couple nights in Krakow, a few in the "country" and then return for another night or two in Krakow before flying home.

2) THIS SKIPS SPAIN AND SOUTHERN ITALY OR CROATIA. Fly into Rome and explore the city for five nights or a week. Get on the June 13 Nine-night Disney Cruise that stops in Messina and some Greek Isles, OR the June 22 Nine-Night that stops in Dubrovnik and Greek Isles. Return to Rome on Day 15, say, and head north - maybe the Dolomites? Maybe train to Venice for a few days, then Lake Bled? Get to the mountains and try to avoid the heat. You could even fly to Munich or Salzburg from Rome and then take a week/ten days going across Austria to Vienna. I love Hallstatt, which has a salt mine; Krems and Melk are also beautiful, and it's fun to bike across the Danube. If you make it to Vienna, you can train (although it take I think 5-6 hours?) to Krakow, where, again, you'll have a week to do the city and explore your husband's ancestral home.

I like making fake itineraries, so take or leave any of this. Choice 2, honestly, is probably still too ambitious, now that I look at it again. Maybe a week in the Dolomites or Alps and then a week in Krakow? I guess my big take-aways would be: Figure out what your priorities are; find places where you can base yourself for a week at a time; and seriously consider a Disney Cruise. It sounds like it will be a wonderful trip!

You haven’t said much about your children; however, I’m going to assume they are like others of their ages.. As a former teacher (40 years in grades 1 - 6), and having raised two children of my own, I can tell you that after a short time, the 12 and 11 yr old will yearn to spend time with kids their age, preferably their own friends. They could throw a pall on the whole trip. I suggest you start off more modestly with a trip of, perhaps, 2 weeks. You will also be able to see how they take to foreign travel.

I would stick to Italy. Get some guide books - - your local library is a good source - - and watch some videos. Let the children help plan. Resort areas like Taormina fill up fast for school holiday times, so make reservations as soon as you settle on an itinerary.

Be forewarned: Sicily and Calabria are likely to be blazing hot in July.

I vote for Allison’s itinerary # 2! We did a 7 night Disney cruise to the Eastern Caribbean when our boys were 8 & 11 and it was amazing! You don’t have to pack/unpack, worry about getting to/from places, and have a combination of family time and couple time (the kids won’t want to leave the kids/tween areas).

We did a 3 week trip by car last summer (Mid June to early July) to Germany, Austria, Slovenia and Venice. That was a lot of area to cover in that amount of time. My husband and I had been to most of the places previously, and were excited to share them with the kids. That said, our sightseeing pace was MUCH slower than on our trips pre-kids. We took breaks almost every day after lunch, then went back out in the evenings. And it wasn’t even really hot yet!

I would identify your priorities: visit family, hit the “top sights”, etc. Find out what the kids want to do (water parks, amusement parks, beach, pool)- if everybody is grouchy, nobody is having fun! Plan no less than 2 nights at each stop. Otherwise the pace will be exhausting. You’ll lose half a day (or more) each time you change locations. Rental car probably isn’t feasible. Your luggage won’t fit in anything smaller than a minivan, and they are not common. So look at trains or flying.

I also agree with the others that you’re trying to pack too much in. Drop at least one country. Personally, I wouldn’t go to Spain or southern Italy in the summer unless I planned to spend the whole time at the beach.

Disney cruises are great, but expensive. Still, if your kids are into Disney, it will be worth it.

I second the idea of taking your first European trip with kids on a cruise. It's a great introduction to Europe and takes care of a lot of things like "finding food everyone will eat" more easily. We did our kids first Europe trip when they were 8 and 11 on a cruise and it was perfect. The husband and I had been to Europe 3 times previously and weren't ready yet to do a land-based vacay with them. After doing that cruise, however, we will try a land-based "plan everything ourselves" vacay next year.

Poland seems to be the real outlier of your trip geographically.

You could do a cruise like these, and spend time before and/or after the cruise in Barcelona. You could even not book hotels for the second half of your trip, and use the cruise to discover places you want to see more of, then spend the last 2 weeks in those places.

Cruise 1: France, Spain, Italy, Croatia, Montenegro (June 25, 2020)

Cruise 2: France, Spain, Italy, Croatia, Montenegro (June 1, 2020) (Italian and Croatian cities different on this one)

How will your children feel about visiting unknown relatives? If they're already grumpy from jet lag, this might be hard. How much long-distance, 4 week travel have your children done in the past and how did they do with it? If all three aren't totally on board with the trip's plans, this trip could become an expensive nightmare. Sorry to be a downer, but better to think through all this now and plan accordingly.

I just got back from Split, Dubrovnik and Trogir and they would not be on my list for children who haven't done much traveling, unless it was on the Disney Cruise. They are primarily just beautiful scenery and obscure history. We traveled a lot with our daughter from birth through college and these cities would not be places she'd want to go even now-she's a London/France/Italy/Vienna kind of girl.