Florence is quite a distance - if you do the ship's tours it is a long day. I would suggest giving that a miss as you cannot do it justice in a day anyway, and just catch the train to Pisa, and then catch the train from there to Lucca - which is a hidden gem, and not crowded with tourists. From Villefranche you catch the bus or the train to Nice. Again Cannes is a bit further on, and I do not think you could do both cities justice in one day. This is a good website: http://www.allaboutnice.com/buses_and_coaches_in_Nice.html. Very easy to hop over to Sorrento - the ferries/hydrofoils stop right next to the cruise ship port in Naples.
Thankyou for your help in excursions. We were thinking of perhaps going on the "Panoramic Florence" trip with Voyager of the Seas lasting 5 hours and "Nice and Cannes on your own" lasting 8 hours with Voyager of the Seas. Have you any thoughts please on this.