Train or Rental Car? Paris to Barcelona to Madrid to Galicia

If it was me, and for ease of logistics.
Fly in to Paris (5 nights)
Fly to Barcelona (3 nights)
Train (2hr 45min) to Madrid (3 nights)
Train (5hrs) to Galicia (5 nights)
Pick up a rental car for your time in Galicia
Fly to Paris (1 night)

On July 26th check flights with Vueling from Santiago de Compostela to Paris via Barcelona.
VY1671 dep 0855.
VY8030 arr 1430.

I suggest checking the estimated costs provided by ViaMichelin. I think you are underestimating fuel costs and/or are ignoring tolls. VM estimates over 350 euros excluding any parking expenses.

Just a question: why not fly back from Spain? Not sure if you already purchased plane tickets? We just returned from an 18 day trip in which we flew into the Languedoc in southern France and out of Barcelona. It was very convenient. We rented a car in France, but then returned it before going into Spain because we found renting in one country and returning in another to be financially prohibitive. We returned the rental car in Perpignan at the train station and then took the high speed TGV train (https://www.voyages-sncf.com) from Perpignan to Barcelona. It was very easy and quick (1 hour train ride vs 3 hour drive). It was so pleasant that we found ourselves wishing the train ride was longer. The ticket was about 19 euros per person. There were slightly cheaper fares available for the slower regional or local trains. My husband drove the whole time in France (and some excursions into northern Spain, Cadaques and Figueres) before we returned the rental car, and he was relieved to be able to just relax and enjoy the scenery on the train. Next time we plan to utilize the train more because it was so enjoyable.

Having a car is nice if you want to visit out of the way places, but if you are thinking to just do Paris, Barcelona and Madrid, you will not need a car, and having one in the cities can be a liability. The traffic patterns are different than we are used to at home, parking is expensive, and the streets are VERY narrow in many areas. Public transit is so easy in those cities, and walking is the best way to really see the city and its neighborhoods. Plus, staying in the neighborhoods of the old town is more fun and convenient for sight seeing, but most of those places don't have parking, and often are on pedestrian only streets ( I recommend Hotel Casa Camper in Barcelona, it is wonderful).

You might just want to rent a car for your time in Galicia. A consideration: luggage space in the rental cars can be quite small, smaller than in the US. If you rent, be sure you get a vehicle with enough luggage space for the four of you. At the same time, if your vehicle is too large, parking and getting through the tight lanes of historic cities is harder. One great thing we found while driving in southern France is that there are rest areas everywhere (on major roads) and they are very nice. The TGV train had a bathroom. Be aware, you may have to pay 0.50 E to use the bathrooms in the train stations in France and Spain.

Barcelona was fabulous, and there is so much to do there. You need to walk the neighborhoods of the old town in order to really appreciate it. Our favorite was the area around El Call and the Born - we kept going back there over and over. We spoke with other Americans that had just been in Madrid, and then came to Barcelona. They felt like there was much more to do in Barcelona than in Madrid.

Whatever you decide, I hope you and your family have a lovely trip. Bon voyage and buen viaje!

Addendum: The writer above is correct, almost all the roads are toll roads and they do add up. Also, fuel is much more expensive than we are used to in the states.

If going directly from point A to B without stops along the route, take a train or fly. The advantage to driving is being able to stop at those places you just come across, and there are a lot of those between Paris, Barcelona, and Madrid.