Three years ago I spent a week in Spain - 2 days in Madrid, 2 days in Girona and 3 days in Barcelona. It is beautiful! I love the old gothic style buildings of Barcelona. That's the area we stayed in. Loved the cathedrals and the narrow winding alley/streets. It's like it's own little world before you walk out into the "city". It's a very busy city. We were so tired from sightseeing that we spent the entire last day on the beach that is literally the edge of the city. The water was wonderful.
I think You will love it as much as I did.