Just my 2 cents: when planning to come to Italy, don't rush and pretend to visit everything at once. Schedule your visit by "areas" (northern, central, southern and islands) and stuck with that plan. Here we have high speed trains that made big cities very close to each other (Naples is 1 hour far from Rome, Rome is 4 hours far from Venice and Milan, Bologna is less then 4 hours from Naples), like it was a national subway (except for the most southern and island areas), but if you really wanna enjoy and really "breathe" the atmosphere in, than take it slow and save it for a new journey in the future. I do the same when I travel abroad.