If Rome has Testaccio, Milan has Isola. Both are areas that have been subject to renewed urban interest, and both have the atmosphere of a village where creatives and locals live side by side.
The last time I was in Rome I stayed in Testaccio, as recommended by a Roman friend. You'll love it, she told me, and she was right.
1. Start your day outside CaffਠVittorio Emanuele in Piazza Maggiore with a cappuccino and brioche (they'll also give you a glass of water to go with it), and watch the world unfold.