The weather in Italy south of Rome is more typically better in March. Le Cinque Terre and Venice do not get warm like the south in March. In Venice you have the problems that if it rains too much it can be a flood that makes it hard to move your luggage. In le Cinque Terre if it rains you cannot do anything. But there is a train so you can leave to go to Pisa.

It is fine to go to Tuscany but there is not a lot of things for children to do in March except if you go to Pisa or Siena. Maybe San Gimignano and Volterra. Orvieto has some things for children. If they are old enough to go to thermal waters and spas, that can be nice in March You go to Saturnia..

Of course if you do not want to go to see Pompeii or Napoli or the Amalfi then you should go to where you would have a nice time that you like. Sometimes in the south in March there are also bad storms. So it is better to take the family where you think you will be happy and forget about the weather.

massimop, you are right. Because we are going at the end of March I wanted to go south of Rome. But currently I am having a hard time coming up with a good itinerary going south. Except for Naples, Pompei and Sorrento. But somehow I feel that I mind find something even better

The children do not really need special kid entertainment but I definitely do not want to fill our itinerary with only museums, for example. A variety of experiences would be nice.

Naples, Pompeii, Amalfi Coast, Sorrento

Joy2, that is probably the most logical choice indeed

personally I would do it the other way round and use Sorrento as a base, then work my way back to Naples and then Rome.