Northern Italy or South?

It's difficult to go wrong with Italy tbh.

But it kind of depends on what you're looking for.

My favourite place in Italy is probably Lago Maggiore, which is up north. Part of the lake is in Switzerland so depending on where you're staying you can visit Switzerland as well while there. Tons of small villages and little islands you can explore and it's also great for both hiking and swimming.

The most south I've been was Salerno and I liked it, but nothing beats Northern Italy and the Italian Alps for me.

No idea. I was quit in the middle at the east coast once when I was a kid, I barly remember anything outside that we did a trip to Venice one day and got scammed there ...

The most classic itinerary in my book would be something like Venice (3 nights) -> Milan (1 night) -> Cinque Terre (2 nights) -> Florence (3 nights) -> Rome (4 nights).

I would probably replace Milan with Bologna in this case though. Not sure how the trains are to Cinque Terre from there though.

South is good but in my opinion the route I outlined is the best for someone who has never been to Italy just because you see the most (in my book).

Naples and Amalfi Coast are great but eh, not a fan for a first timer.

Sicily is one of my favorites, but same deal applies.

Venice is an absolute must for anyone that likes art, history and architecture.