I think you would be just fine bringing cruise/summer dresses to wear to dinners. Everyone "cleaned up" for dinner, as one poster mentioned, and I felt like I didn't bring enough dressy clothes. Not that wearing less dressy clothes was a problem, but it would have been more fun to change into something pretty at night. The restaurants, while "family style" in some respects, were also quite nice - tablecloths, three course meals, wine, etc. Many of the women in my group not only wore nice things at dinner, but pretty summer dresses during the day. So - bring whatever makes you happy! And remember that summer trips can be very hot, so you'll be glad for a change of clothes after touring all day.