For sure, do NOT eat at the Galleria. Perhaps a coffee or a beverage but the food there and in the area is overpriced and underwhelming.

If you are driving in, the area around the Galleria and La Scala is in the ZTL so don't drive to it. As Marriott Silver, there is a nice Marriott on via Washington and you can park around there. There is a nice Neapolitan restaurant just up the street from the Marriott that is good and reasonable (as I recall).

Alternatively, I would second the Naviglio for a drink/dinner. One weekend a month (I believe the last) there is a nice flea market there as well.