Greetings: What is the best way to travel from Rome to Vasto? Bob
Define what best means to you. Are you willing to drive or do you want public transit? It does not look easy or quick, likely involving two long bus rides.
Train or bus, not car.
Check Flixbus for routes and prices. They are fairly reliable and relatively inexpensive. https://www.flixbus.com/bus/italy
Train (Rome to Pescara, then Pescara to Vasto).
www.trenitalia.com
or Flixbus