You should understand in advance how much you'll likely spend on excursions and how that cost compares to what you can do on your own. Not at all, but something you may want to keep in mind as you tour. There are two factors to the success of a tour - the operator, and the guide. You can, and should, check out the operator in advance. You'll rarely know who your guide will be until you meet them at the airport or hotel.
Some guides are great and all their clients come away highly satisfied.
Touring, especially in Europe, and doubly so in Italy, is a tricky thing because of irregular closing days and opening hours of museums and other attractions. The tour origianlly organized to go from Rome to Milan over 6 days beginning on Tuesday may not work so well starting in Milan on Thursday. These are a major expense for the operator. They're written by creative writers. The adjectives and adverbs, or the missing ones, are the tricky part.