Ginny, I did this several years ago, and did the Deluxe Italy by Rail with Perillo Tours. Wonderful hotels, some meals included. This was the best tour they had available, as most of their tours are "first class" rather than "Deluxe". It only went to Venice, Rome and Florence, and as I remember included a side trip to Siena? Lots of time on your own, but guided tours most days for at least 1/2 day. Best guides I've ever had. Italy has stringent qualifications for certified guides.

I believe ChatKat has also had experience with Tauk tours, and they are very nice. I'd check both websites to see what appeals to you and your time frame.