Have a wonderful time. Barcelona is a beautiful city with lots to see. The food is wonderful. Beware of pick pockets in the Ramblas (long avenue that runs to the ocean and is full of cafes). Just take the usual precautions (don't carry anything in back pocket and keep you camara and valuables close). Barcelona and Venice are two of my favorite cities. I find Venice very romantic. It's great getting lost in the alleys. If you get a chance to do the Duomo tour...do it. You will need reservations (you can go online) to avoid the crowds. Go to Monserrat in Barcelona if you get a chance and don't forget Gaudi's cathedral (never finished) The Sagrada Familia.
Have a wonderful time and bon voyage!!!
Pili