I'm not sure what kind of information you're looking for but you'll find most of the top designers there (don't recall seeing a D&G store though, but they do sell it at Corte Ingles). Try Serrano street and Ortega y Gasett (off of Serrano). Prada is on the corner of Goya and Serrano, Armani is on Ortega y Gasett along with Chanel. Also head to Corte Ingles at Nuevos Minesterios, they have the best designer sections at that location.