I'm leaving for Italy in a couple of weeks and will be spending 11 days in Rome, 8 in Florence, and then a week driving the north. I plan on eating in some high-end restaurants, and was wondering what the norms, as far as dress code go, are? I plan to pack a sport coat, dark Dockers, and black walking shoes. Should these be sufficient? Thanks.
Italian restaurants can't refuse service because of the way people dress.
On the other hand, I bet you want to feel comfortable and avoid being always seated next to the toilet's door. If this is the case, a "Business casual" look should be more than enough.
Unless they are German, men should never wear shorts, sandals and white socks.
Long pants, a shirt, and sport jacket, and you will be dressed more than adequately even for the Enoteca Pinchiorri, certainly the highest end restaurant in Florence, and maybe Italy.
I doubt you will be dressing like a stereotypical German tourist (Shorts, sandals, and socks) in April. The weather is generally pleasant but not necessarily hot enough for shorts, especially in the evenings.