Which airport in Milan? There are two - one is close (Linate) and one isn't (Malpensa). From Malpensa it's about a 50-minute bus ride to the Centrale train station, I think it's like 7 or 8 Euros round trip. There's also a train from Malpensa to another part of Milan but I haven't ridden that.

If I had 10 hours to kill in MXP I'd go into town for a bit. Just leave enough time at the end to get back , check in, etc.

But is that the best itinerary you can find?