As I arrived few nights before my friends I actually stayed at two different places in the Navigli area. The first of these was perfectly located along the canals (booked via airbnb), and the other some 600m away. The Airbnb place wasn’t anything special so I wont cover it here, but the apartment hotel where we stayed is definitely worth recommending.
We booked our lovely studio at BB Hotels Aparthotel Bocconi via booking.com for 109€. The apartment had been recently fully renovated and was both spotless and spacious. Our studio could have easily fitted 4 people on the double bed and the sofa bed.
The staff at the hotel was also super friendly and were always ready to help out. I did have some issues with Wifi but I believed the staff when they told me this wasn’t usual and I felt they did everything they could to fix the issue.
The hotel is located slightly outside the city, but honestly I wasn’t bothered by that. It was only some 600m from Navigli, and you could walk to the Duomo in some 20minutes – unless you wanted to take the tram.
If you don’t want to stay in the Navigli area (which is where I plan to always stay in the future), other option I would recommend is Brera, the artistic center of Milan located right in the center.