I can only recommend staying at Sergio & Anastasia's when in Milan. The location is excellent, it's a beautiful building and their apartment with it's little balcony is really charming and you feel right at home.
Even though Sergio couldn't be there to let me in, he gave me directions, so check in/out was uncomplicated and everything was pre-arranged for my stay. They even had prepared some pastries and pistachio creme for breakfast! :)
All around good experience, and would definitely come back.