I highly recommend Tuscany and Emilia-Romagna: both regions have many beautiful and historic cities, including very nice smaller ones (Ferrara was a highlight last time I went to Emilia-Romagna), as well as relaxing countryside. Rome is also fantastic, it probably is one of my favourite places I've ever been to and I'd love to go there again. As for other places, Milan is also neat, and the Italian lakes' region is very nice too. Sadly I've never been to Southern Italy as of yet, so I can't say anything these regions.