United and American Airlines have flights from Dallas (DFW) to Milan (MXP) starting at $459. Flights in March, October, November, December, and January. No Christmas. Flight may operate as a Oneworld/Alliance code-share.
Note: New Years is available if you can do an 11-day stay or longer.
Note: Fare allows for a free carry-on bag, but checked bags will cost about +$60 each-way. You can avoid paying a seat selection fee by accepting the free, randomly assigned, seat at the gate.