I am trying to see if the campania arte card is worth it for two adults and a 9 y.o. child. We will be based in Positano, and plan to vist Paestum, then two days later, Pompei and/or Herculaneum on the way back to Naples train station (so we could use the card within the 3 days).
However, I probably wouldn't take advantage of the free transportation. I think it covers the local train pompei/naples, but not sure if we will have a driver take us from Positano to Pompei, and wait for us, then drop us off in Naples. We will have luggage with us.
I have also considered going on to the naples archeological museum from Pompei, before taking the train to rome (and leaving our luggage at baggage check at the train station)