Head for Gracia in Barcelona, it's 'proper' Barcelona, very left-leaning, laid-back, authentic, chilled. Head for Fontana metro on the green line.
Lots of good bars to suit the likes of us. I go in two neighbourhood places on c/Mozart - Ballbreaker (a rockers' bar) and, down the road, the more laidback Kimera.
KGB is a gritty club better than the masses of cheesy euroshit places.