The Lake Como area in Italy should be very nice. I have not been there in the Autumn, only in the summer. Maybe venture a couple of hours north into Switzerland also would be in order too. And of course, here in Southern Germany has a lot of nice places for fall colors. The Allgäu Alps/Lake Constance region is always beautiful. Another wonderful opportunity for fall images is around Hohenzollern Castle here in Schwabenland.
Ah, you've reminded me of Van Ludwig's castle over near Fussen...Neuschwanstein
When are the colours usually set to arrive and for how long does the colour usually last?