After the ultimate guide to Barcelona written by Gonzalo (great job indeed, congratulations!!!)... I can can only recommend you to watch a movie if you have some spare time: It's Woody Allen's "Vicky Cristina Barcelona".
"The plot centers on two American women, Vicky and Cristina, spending a summer in Barcelona, where they meet an artist who is attracted to both of them while still enamored of his mentally and emotionally unstable ex-wife María Elena. The film was shot in Avilés, Barcelona, and Oviedo, and was Allen's fourth consecutive film shot outside of the United States. The film premiered at the 2008 Cannes Film Festival, then received a rolling worldwide general release that started in August 2008 in the U.S., and continued in various countries each month until the June 2009 release in Japan." (Wikipedia)
I think that the mix of Penélope Cruz, Scarlett Johansson and Javier Bardem with Barcelona's landscape is fantastic and even if you like or not the movie, you'll surely get an appetizer of the city's environment.
Enjoy and let me know if you watched it and your impressions as well!