We are preparing for a trip to Italy next year and my wife mentioned that she was hoping to see castles. My understanding is that Italy doesn't have the same kind of castles as say Germany, but are there any that you would recommend visiting?
http://www.walksofitaly.com/blog/all-around-italy/ten-of-the-most-beautiful-castles-in-italy Let her make her choice.
There are also plenty of hotels located in castles and old manor houses. I don't have a specific recommendation in Italy, but such a stay could be a highlight of your trip! I'm sure you can search online for them.
Just google "Castles in Italy" to see tons of choices.
I was watching your question because I was also interested in this topic. After clicking through the links provided by others, I found this castle: http://www.odescalchi.it/pagine.php?idx=89&pg=13. It is only an hour train ride outside of Rome. Just wanted to point it out to you, because I am guessing your trip is likely to include Rome.