I was there about 3 years ago for 26 days. Most of these were dedicated to Catalunya and a bit to the border French area.

In Catalunya I MOST recommend:

Barcelona - Mid Ages, Modernista and Modern (Olympic period)

Montserrat

Monasterio de Poblet + Montblanc

Tarragona

Tortosa

Girona + Castel de Pubol built by dali for Gala

Teatro Museu Salvador Dali in Figueras

Port Lligat of Dali and Cap de Creuz and other Costa Brava's paradises

Olot, Besalu and the area

Collioure of Henri Matisse (France) + Perpignan

From there I had a train to Carcassonne - the real Medieval fortress.

Then you can continue to Toulouse, close to each there are Albi and Montauban.

From Toulouse there is a bus Andorra from where you can make a back ride to BCN.

If you anymore specific question - I'll be glad to answer.

Sincerely,

Alex Elbert Jerusalem Israel