thought we'd head to Milan since we wanted to go to Como lake area Milan is so close. Would an overnight trip be worth it? Thanks for any opinions on this
Milan is in Italy so you may not get all the feedback you are looking for here on MySwissAlps. I've been there once, but since I'm not too fond of big cities that one time was enough for me, and I'd rather focus on nature instead. Of course if you have a particular goal, like the cathedral, museums or if you love shopping, it can be totally worth it.
Arno has said it well. if you know why you are going, for specific items, yes. Otherwise, long trip, small value.
Why not spend more time in Swiss places? How long will you be there?