Navigli and Lake Como are probably my favorite places from Milan. Forget the Last Supper at the Santa Maria delle Grazie and the Duomo di Milano, these are the real gems of Milan.
Navigli and Mercato Metropolitano
It's very common to hear about Milan as a metropolitan city. Many liken it to New York City or other, vibrant centers of culture and business. The Milan that I saw and loved was partly this Milan, but also the quiet, less outspoken Milan.
The place to be is Navigli. Super cool, hopping joint in Milan. Definitely the most hipster neighborhood in the area. The market in the area, Mercato Metropolitano, is a gem. Reminiscent of the Brooklyn Berg'n Hall (but way bigger and much better), the space is utterly crowded on a Saturday night. Bonus: shipping crates repurposed into legit bathrooms. I've heard of this but man, it is awesome.
And, to top it off, Navigli also houses a fantastic little gelato place, Gelateria Orso Bianco. Yum.
Lake Como and Bellagio
I will make the controversial statement here that Lake Como has one of the most beautiful waterfront scapes in Italy. And I'm including Cinque Terre and the Amalfi Coast. Really.
There's really something about the train up to Varenna Esino, and the boat ride to Bellagio. Coming up to the town is really just spectacular. The town seems really unimpressive from the dock, but walking up and down the winding, hilly town is a great way to spend an afternoon.