Hej pa dej. Now that is at least an interesting and not often posted Question here.

Normal answer on all  these wide+broad Qs is always: depends what you like. Obviously trains mostly serve larger towns, not tiny villags far away in nature.

There is a railline all along the coast (In ESpana north of Barca even right along the beach) to the Italian border. So ALL larger towns along it have stasioner and easy to reach and even free too-IF you use the local regionaltoger. RENFE rodalies Catalunya Express to Cerbëre, change (from wide sp to normal FR gauge)-you pass Perpignan, Narbonne (not very interesting), NImes, MOntpellier, Beziers, Avignon, change for onward (train ends). All these places have their merits and are mildly interesting.

There are also plenty of beachy areas-at some the train also passes very close by, like Alës.

Its all FRench-so plenty of hotels and places to eat and touristy offices for more info. IF you plan to visit more as 1-buy local (reduced for seniors) tickets between the 2 for short distance.

In Narb you can also change toward Carcassonne (very famous)-Toulouse-Bordeaux.

You can use the superfast TGV/AVE trains to shorten time in train-but there are very high Surcharges and they make less stops.

There is also the INland route from Bcn to La Tor de Carol-at one but last stop in ES you can change for a bus (payable) to Andorra=visit an obscure small country not many have been, no rails). From LTdC change to FRench local=TER train-toward Toulouse.

Hello there

I was at the French and Spanish coast just a few weeks ago.

I really can recommend Tossa de Mar and the whole Costa Brava in Spain and Cassis in France (next to Marseille).

Last year we went from Valencia - Barcelona to Port Bou - Cerbere with local  trains. In Cerbere we have to wait te take the sleeping train to Paris. From the station we walk through a long tunnel downstairs and we stand on a beach! With little shops and bars. It was very nice!

Look in the south of French if  you see flmingo's near the train in the water