45 minutes out of Milan is Lake Como. Add it to your side trip. Spend a week you will not run out of things to do. There are wonderful lake towns sprinkled all the way to Switzerland. You take one of the boats out of the city of Como and travel up the lake towns until you come to the town you want to discover. One of my favorites is Bellagio. The cobblestone streets, the flowers, the lake, and the genuine friendliness of the people who live on the lake. You may stroll, walk, or hike whatever your pleasure. I would encourage you to stay a night or two in one or more of the lake towns.