As we design our itinerary for fall 2018, we are deciding how we would journey from Provence to Seville and Granada by train. We will spend 2 nights in either of the northern cities or another if you have a recommendation (we have looked at Valencia) as we strive to maximize our explorations and sensory experiences while breaking up the train rides.
Where in Provence? Aix has trains to Barcelona, a manageable trip. Barcelona is certainly worth a visit. There is a high speed train to Madrid. Then training to Sevilla and Granada is pretty easy.
Except for the art museums in Madrid, Barcelona would be much higher on my list. Plus in culture, food and architecture, Barcelona is completely different than Sevilla and Granada.
You have direct train services ....
Marseille to Madrid
Madrid to Sevilla
Marseille to Barcelona
Barcelona to Sevilla
... so it really matters not.
Both places are worth more than a 2 night stop if you've not visited before.
I would look at train, bus and plane schedules and get an idea of how long it will take you to get from place to place. One would hope that by fall 2018, the train track upgrades will be complete and there will be high-speed service to Granada. In the meantime, Barcelona-Granada by plane is the best option. Right now, I'd have to say . . . wait a year and see what the train schedules are like after the upgrade is completed (it was scheduled to finish last October). Valencia is an outlier.
Sounds like Barcelona is the what we are looking for to begin our excursions in Spain. We will keep tabs on the progress of the new more direct train options. Thank you for all the helpful tips and recommendations!