When you like to stay in Navigli, Michele's place is perfectly situated. The bus stops in front of the house, which can bring you to subway station Porta Genova in just a few minutes. I prefer walking, it took me about 45-60 minutes to walk to the Piazza del Duomo (which for me was fine). But Navigli itself is great to stay in, there are so many shops and restaurants that you don't have to go to the centre at all. Besides that, it's also a lot cheaper :)
Michele is a really nice guy, easy to talk to. He provided me with lots of directions how to get to his place, and offered to call a taxi on the day of my departure. Besides that, he had some great tips for places I could visit.