Europeans are more dressy than Americans. So linen pants, khakis wore with polo tees or linen shirts are recommended. Shorts will be appropriate on the cruise but not in some Italian churches.
I always travel with at least one sport coat. It will come in handy for evening functions. So bring along a linen or tropical wool unlined S.C.
A collapsible Panama hat will add a dash of style in addition to shielding you from the hot Southern European sun.