driving from Tuscany to Avignon

As I recall it's a good ten hours from Florence to Avignon. Presuming you are driving first plot out a route that is of interest to you and although it has all the charm of a Motel-6 check out the Ibis hotel chain or ETAP (step down from Motel-6 but clean). We drove from Florence to Avignon three or so years ago and made a day of it. Wonderful lunch along the way, a few sights etc. Toured Avignon the next morning and booked after lunch.

Viamichelin estimates 6 hours from Lucca to Avignon. Lucca's about as near a starting point in Tuscany as you can get so add a couple of hours if you'll be starting from closer to Siena.

There's really only one route - the Autostrade along the coast through Genoa and then into France near Nice. If you can, stop overnight somewhere on the Riviera - maybe Villefranche sur Mer? But book early. Depending on when in May you'll be traveling you could get shut out by the Monaco Gran Prix or possibly the Cannes Film Festival. I wasn't very charmed by the Italian Riviera towns - lots of crowded highrises and rocky beaches.

You would be wise to check into the cost of a drop fee of your rental car. That could be very expensive to return car rented in Italy at your France destination. We have always taken care to avoid this expense. Have a great trip!

As Susan says, you will pay a substantial fee for picking up a car in one country and dropping it off in another. It may be cheaper to rent two cars. Drop the first one off inside Italy near the French border, take public transportation into France, then pick up the second car. San Remo would be a good drop off point and Nice would be a good pick up point. There is frequent train service along that route.