One of the best street in Rome for shopping is via Borgognona. It is a pedestrian street, no cars at all. It is not too crowded because often people prefer via del Corso which is more commercial. In Via Borgognona a lot of elegant boutiques but also some affordable ones. You can find hip and cool stores such as Stella Mc Cartney, SportMax, Les Copains, Brunello Cucinelli.
When I talk about affordable boutiques, I speak about Cos and Other Stories where you can find skirts, blazers, coats but also dresses and shoes. In Other Stories, for example, a great selection of Adidas Sneakers. It is also the street of a great historical italian restaurant : NINO where you can get fantastic pasta and vegetables cooked roman style..