I voted 3 (Rome, Venice and Milan) and will add Tuscany too. The problem is that the first 3 are riddled with tourists, especially during the summer season, so I would suggest you go in Autumn or Spring, you also avoid hot sticky weather that way.
Italian Pizzas are fantastic but don't order one with pepperoni as it doesn't exist there unless you find an American Pizzeria there. Pepperonis are an American invention/creation.An italian can confuse it with you ordering peperoncino which are thin red or green peppers and it has nothing to do with peperonis at all☺️
@ElwoodBlues Thanks! The same goes for my country actually (Spain) and most Mediterranean countries too where summer is a fun season : parties, swimming, concerts but better go around late September or october , it's all still happening at that time but less heat and cooler nights and cheaper too because it's not at the height of tourist season anymore ☺️