My itinerary:
Barcelona to Valencia. My uderstanding is that there is a local train from the airport to the el prat train station. It's my understanding that from El Prat I take a train to Valencia.
Valencia to Seville.
Seville to Madrid.
Madrid to Sitges
Sitges to Barcelona. My understanding isa that you take a commuter train to the el prat train station, and take take another train to the airport.
From what I can gather my best bet is to book my tickets through trainline.becaue they exhibit all the connecting trains.
I understand that trainline does charge a booking fee. What is your experience with trainline?