Playing for two days, I bought a 48h card, which includes the subway fare for departure from the airport. Besides, there are only 48h cards for t2. The one who goes to T1 subway station for 10 times is more economical than Madrid's. There is no card fee. Besides, Barcelona is indeed a big city in 70 minutes. It's very grand. The houses are all of various kinds, super-featured, and the basic scenic spots are all around. Around Gaudi's art, it's enough to choose one or two. I think more time can be spent in feeling the city and relaxing myself.