I've been to the Costa Brava (north of Barcelona) and some of the courses there are nice, but in my opinion far from world class. Emporda is completely artifical and doesn't match the surrounding land at all, Catalunya is a PGA course, nuff said. Platja de Pals is a nice resort course, but nothing you wouldn't find in any of the other areas mentioned. The Marbella region is visually dreadful, zero coastline, only hotel after hotel and the courses nothing special either.
The best ideas I've heard on this thread are Valencia and Biarritz. And I would not rule out Italy. True, most of the world-class courses are in the pissy North, but there are at least two great courses near Rome: Acquasanta and Le Querce (yes, Fazio, and I loved it). Olgiata is also supposed to be good, but I haven't played it. However, don't expect "resort amenities" there...
Ulrich