The bars and clubs of L'Eixample tend to attract a slightly more mixed age group than those of the Old City, and more of a classic nature. They are also more spread out, so you may find yourself hopping in and out of cabs if you plan to barhop.
Alhough the area is filled with small squares and hidden corners, the center of the Gràcia world is Plaça del Sol. In the summer, it's the best place to head to meet young Catalans and to watch people on their way to party. Just as many take their own cans of beer as buy from the bars around the square -- the atmosphere is noisy and fun and drives the neighbors mad.
Barrio Alto is sometimes seen as a world of its own. Here is where all the rich families live, in houses no less (something unheard of down in the city), and many of them never leave their enclave. The same applies to going out -- rich kids aplenty, alongside some normal types -- flood the area. The main bars and clubs are concentrated around a street called Marie Cubí, around 10 minutes' walk from the nearest metro stops of María Cristina and Les Corts or FGC suburban line stations such as Gràcia. They're all very quiet during the week, though.
The Catalans call their own version of sparkling wine cava and it comes from the nearby Penedès region. In Catalan, champagne bars are called xampanyerias. With more than 50 Catalan companies producing cava, and each bottling up to a dozen grades of wine, the best way to learn about Catalan "champagne" is to sample the products at a xampanyeria.
Champagne bars usually open at 7pm and stay open until midnight or later. They serve a small range of tapas, from caviar to smoked fish to frozen chocolate truffles. The traditional local time to go is on a Sunday afternoon, when entire families will have a pre-lunch sip. Most establishments sell only a limited array of house cavas by the glass, and more esoteric varieties by the bottle. You'll be offered a choice of brut (slightly sweeter), brut nature, or rosat (rosé, or pink champagne).
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.