As previous posts suggested, I too would recommend taking the Malpensa Express which departs from Terminal 1 for Milan's Cadorna Rail Station every 30 minutes. It also stops at Milan Bovisa and Saronno stations. First train departs Malpensa at 06.45, the last train departs 21.45. Journey time is around 40 minutes. {Fare - may not be current: EUR 9.00 one-way. Same day return is EUR 12.00. }

Easy connection from train stations to subway for any place in the city. With the avail time that you have, the Piazza del Duomo would be an ideal focus. Check out the Gothic church. Stroll inside and around the Galleria Victorio Emanuele (a large upscale shopping mall).

I had lunch and dinner near the Duoma several times on different trips. Unfortunately don't remember the names. For very casual dining, however, I remember there is an Italian buffet styled restaurant located on the Duomo square. When you are facing the Duomo, it is on your right. Order food on 1st floor (street level), you can bring you food up two flights and pick a table where you can see the Duomo. I enjoyed the meal and the view so much that I went back again the next trip. By the way, the food was excellent and the price was moderate.

If you are a history and art buff, take in the Last Supper by the Master Leonardo da Vinci, at the Santa Maria delle Grazie (go by subway).