El Salón del Prado, Calle de Prado
This retro style cafe is a great place for chatter in the evening, with the classic jazz sounds barely audible over the throng. Perhaps they save the grand piano in the corner for when it gets really busy. Appropriately concomitant with the bustle is the bright lighting, which is saved from killing the atmosphere by the stylish decor.
This place was also great when I visited at 2.30 p.m. - totally empty, but the stylishness and cool jazz remained. With the whole place to myself there were probably few enough distractions for me to actually get some work done, while sitting at the bar drinking my coffee. Unfortunately, I had to go somehwere else for lunch, because they only seem to have cake.