Not sure how "different" you want your experience to be, but I would recommend buying books on Gaudi before you go and/or history of the Spanish Civil War and/or acient history of the Romans, Some good books are George Orwell's "Homage to Catalonia" or Ernest Hemmingway's "For Whom the Bell Tolls".
When I was in Barcleona, I used Orwell's book to give me a guided tour of his experiences during the Civil War.
I used a mini art book on the 19th/20th C, art nouveau to get a tour of Gaudi's art, both in English and Spanish. I really like all the art during the turn of the 20th C., there are some really good bars that still have the art and use to serve (and some still do) absinthe. That might take a local guide to help you.
I also had an interest in the Romans and the history of Barcelona. A well hidden musuem is the City Museum, which is located off of Las Ramblas, next to the Cathedral. It has an old "winery" and other architectural ruins that is pretty interesting to look at.
http://www.bcn.es/cgi-bin/iveure_eq.pl?id=92086011563 Have fun and good luck!