Found this website with some interesting info (hasn't been updated recently, I don't think, because they mention " A giant new south terminal is expected to open in 2009.")
Verify anything that really needs accuracy, which should be our SOP, anyway.
http://www.traveltips24.com/Barcelona.htm
Barcelona Weather
"Given the high humidity, 19-23 degrees Celsius is considered comfortable weather, which is normally the temperature
between april and june and between late september-november.
This is the best time to visit the city. Anything warmer than this can feel too hot."
Festivals and Events
"Sant Jordi. 23rd of April. Considered to be like Valentines Day. People give roses and books around the streets. Traditionally men give women roses and women give men books.
It is one of the most popular and interesting celebrations in Catalonia.
Airport Luggage lockers: Someone asked about this
Baggage storage is 4.60 per day for a large locker that easily fits 2-3 serious suitcases. Left-hand end of Terminal B, behind the Ars cafe.
Language
Barcelona's official languages are Catalan and Spanish. However most signs are indicated only in Catalan because of political reasons. Luckily Spanish and English are also widely used in public transports and other facilities. As in most European countries any attempt by visitors to use the native language, in this case Catalan and Spanish, is always appreciated. The majority of Catalans instinctively address foreigners in Spanish. Catalan is a language, not a dialect and sounds close to Italian and French in many ways. Try to avoid referring to Catalan as a dialect, which will probably offend Catalans. Around 30% of local people consider that Catalonia is a nation, with its own culture, history and traditions, to them different from the other regions in Spain. Bullfighting and flamenco is not so popular in this region but the differences are actually quite few. The identity subject might be a very sensitive one among certain traditional Catalans. Moreover, speaking in Catalan to Spanish speaking Catalans might also be a sensitive issue.
On tourist areas almost all shops and bars have some english speaking staff. But english is not very widespread among spanish people, not even among young ones. They are kind and will make an effort to try to help you if you talk in english but their vocabulary knowledge will be very limited. If you do find a white fluent english speaking barcelonian it is most likely to be born outside of Spain, usually an european or latin american inmigrant (both groups being a very significat part of the city center inhabitants along with the not so integrated asian and african inmigrants -which, of course, also do have english knowledge-)."
Sightseeing
La Rambla. The most famous boulevard in Barcelona stretches from the harbor to La Plaça Catalunya running through the Ciutat Vella like a spine. Come here to
see the street performers jump out at unsuspecting tourists, enjoy the flower and pet stalls, or just sit back and watch all of Barcelona walk by. During the day, La Rambla is packed with tourists, at
night, the locals come out, as well as many prostitutes. There, you can find newspaper and book stands, birds, flowers, musicians, street-performing artists that all contribute to create a lively and unique atmosphere. If you happen to be here after Barca win, you're in for a treat!
The Montjuïc Castle. Provides a beautiful panorama view over the rest of the city.
Take the harbor cable car* to Barceloneta for more splendid views. The Montjuic Castle is in the Montjuic Mount, in which you can visit so many places, like the museums MNAC, Caixafòrum, El Museu de l'Esport Olímpic and El Museu Miró. Note: * Jun-Sep: 11am-8pm.
L'Aquarium The second biggest aquarium in Europe (after that in Genoa). Watch thousands of fishes, penguins and sharks in this interactive sea-life museum. Unlike Genoese Aquarium it has a long glass "tube", where you can walk watching sharks and other fish swimming around. Located at the Port Vell leisure center, next to the IMAX cinema. Entrance ticket - 16.
Food
A treat to try that no travel guide mentions is
waffles sold at street stands. They will tempt you with their mouth watering smell and taste.
Even though tapas restaurants are now all over the city, tapas itself originated in Andalusia in the south of Spain and is NOT native to Catalan cuisine. Catalans generally eat three course meals (appetizer, main dish and dessert), and would more likely go for a pre-dinner drink and pintxos (Basque counterpart for tapas) at a Basque taverna.
Near Sagrada Familia on the Carrer de Provenca (across from the church, and next to the McDonald's) there is a buffet style canteen with large windows facing the Cathedral. You get a dinner (unlimited snacks, main dishes, drinks, tea/coffe, deserts) for 10.30 and credit cards are accepted. Open 24h.
In several supermarkets you can find a wide stall with a great selection of ready-to-eat dishes. You can get a two-course lunch for less than 5 euros.