Italy is a big country in many respects. Here are some thoughts:
Florence is a good starting point, with many day trips either by public tran or private driver. Good selection of hotels, good selection of restaurants.
Verona relatively untouched with Venice real close - think an hour to an hour and a half train ride in rush hour. Food and wine excellent. If you are adventurous the small towns between Verona/Venice and Trieste are wonderful and a foodies dream.
Bologna boring not worth your time. The Ferrari and Alfa Romeo museums worth a visit if you end up their. Ducati not worth it and they are a pain to deal with
Postiano is ok, I hate Naples and most points south of Rome. Attitude and crime being the major reasons. Pompeii is worth a view. I would do Cinque Terre or Portofino personally
Sardinia is wonderful food. sights, and it is off the beaten path. Park yourself on the NE coast if possible. Now how good is your Italian? English is a rarity in Sardinia, that said if you know Spanish you can Navigate.
Sicily good option West and North are your
Good luck and enjoy the Holiday
“Better a true enemy than a false friend.”