Driving from Florence to Rome in March 2010. What is the best (most scenic ) route to drive. We are dedicating a full day to make this drive. Mind you, we don't want to be in the car for 8 hours; we want the best route to take.
Take SS#222 just south of Florence towards Siena, then maybe switch to SS#2 (Cassia) to head into Rome... SS#222 is one of the most beautiful roads in Italy, cutting right through the Tuscan hills.
As suggested by Steve, you could come into the A-1 at Orvieto... the back way into Orvieto (incredible view from above the city) is also quite beautiful! Good Luck!
Since you're dedicating all day to the drive, I assume you plan to make a stop or two along the way. The SS#2 that Ron recommends has several great towns that are only a short detour off the SS#2, such as Montalcino, Pienza, Montepulciano, Orvieto and Civita.