Your trip is quite well balanced : south, central and northern regions of Italy, distributed in a reasonable lapse of time.
What you should know about Sicily.
Although belonging to Italian territory since 1865 Sicily has always shown a complicated relation with the Italian State/Nation . It is well known that Sicilian people feel themselves more Sicilian than Italian. For a strange paradox of History, despite (and due to) the continuos foreign dominations in the centuries (mainly Arabian and Spanish ) this people developed and maintained a strong sense of identity. We are not far from the truth if we say that even after Italy unit in 1865..still Sicily looked at the central Italian State as a sort of dominator rather then feeling part of it. This situation created the cultural basis for the developing of another State into the State: the Mafia.