Loved Collioure although for a small town it draws a crowd in summer. It is gorgeous and has plenty of places of interest. The beach in town is pebbly and popular but swimming between the fort and that iconic church is pretty special. Plenty of quieter beaches nearby too.
From Collioure it is a short train ride from Perpignan. From there the one euro bus will take you inland to the wonderful village of Villefranche de Conflent. From V de C you can take the open topped Little Yellow Train to Latour de Carol and connect to Barcelona.
That is a few days of good fun and great sights.
Templiers Hotel in Collioure was pleasant accom. The wonderful old Post Office B&B is the place to stay in V de C.
If you take this route to Barcelona be careful you don't find yourself wanting to linger longer than you planned.