Italy is a big place and very regional. It also pays off to think about what you want and to do a bit of research.
As with everywhere, if you go somewhere massively touristy and popular, you are going to get ripped off. If you have pizza on the Piazza Navona in Rome, you will have an amazing view while you eat your pizza, but the pizza will be terrible and you will pay through the nose for it.
It's also worth thinking about what the local food actually is where you are - if you eat pizza in Venice it will be dreadful because pizza doesn't come from Venice for example so it's just horrible mass-produced stuff for the tourists. The local food will be cheaper and better. Avoid anything saying tourist menu at all costs.
Similarly Sorrento is expensive, Tuscany is lovely but more expensive than Umbria which is next door but not as well known so cheaper, and La Marche is cheaper still.
Beaches - make sure you aren't going to an Italian resort as they will be lined up like sardines!
All the nicest places we have stayed have been agriturismos. We tend to have a plate of ham/cheese at lunch time when out and about and then main meal in evening - if your agriturismo does food it will likely be amazing.