I’d go against the grain and say Rome in August is fine if you don’t mind the heat. We always go in August (family live nearby) and yes it’s hot but it’s actually less crowded as the Italians go to the beach, and tourists have been scared off. May and October are much much busier. The buildings create wind tunnels and there are water fountains everywhere and lots of cool churches to pop in to escape the sun.
Is there a type of place you’re trying to see, or things your kids like to do?
Croatia is stunningly beautiful but the coast versus Zagreb are very different. I love
both and we did both in one holiday and it was a great contrast.
Italy - Im a huge fan of Puglia and its little white hill top towns in southern Italy, and Turin in the north is an incredible city with fabulous museums (Egyptian, Car, Art) - a great winter trip as weather might not be great but you’ll mostly be inside visiting places. Also a good tunnel network under the city you can visit.
Belgium is much overlooked, but easy to travel around and the smaller towns like Dinant and often overlooked but beautiful.
Poland - we loved Warsaw, Krakow was lovely but very touristy. If you don’t like the cold avoid before March.
Germany - Berlin is an amazing vibrant city with so much to do and very easy to get around. Munich is smaller but very family friendly. The German lakes expensive but glorious scenery and lots to do outside and museums. The black forest too is more spread out but fantastic sight seeing.
Switzerland - more expensive but wonderful rail links so easy to get around and tick off a few places very easily.
France - has every option, but I love Brittany but I’d definitely want a car there as stuff is very spread out. I don’t love Paris but plenty do! Montpellier on the south coast was a surprise (a good one) and I fell in love with Dijon (small but so much to see) in the East.
Spain - San Sebastián in the Basque Country, Valencia, don’t overlook Zaragoza which is a fantastic under-known city in the centre. It gets hot, and stay on the historic side of the river, but it’s so alive and full of history.
Portugal - obviously Lisbon, Porto is great but might be under utilised with kids as it is very centre around the Port trade. The Algarve is all about relaxation and enjoying the summer.
So yes, for me it would depend on if you’re trying to tick cities off the list, or famous landmarks, or really get to see countries in which case some of the lesser known places can be the best!