We did this last year, starting in Rome (stayed in the Napoleon Hotel), taking in Florence (Hotel Cristina), Sienna, and Assisi. Would absolutely recommend it, we loved evry minute of it. The food, the drink, the people, the service - they put us to shame in this country! We didn't go near any beaches so can't help you out there but if you are travelling around Tuscany then by car for me is the best way - you can do things at your leisure. In saying that, the train service is excellent, and reasonably priced too.