Florence to Rome
 

Any suggestions on where to stop for lunch, how much time do we need for Sienna, we are driving, is th etown of Asiss worth going to

Orvieto--plan on 3 hours.

I think you should read up on Assisi, see some images of the town and basilica and see if it looks like something YOU would be interested in. It is indeed worth going to, as millions do, but if it's something you might like is your call.

I stayed two nights in Sienna but you could see it in a few hours. You'll want to see their Duomo--very impressive for a small town. At one time they were in competition with Florence for the area's largest/richest cities and the Duomo was where they showed that off.

The Piazza del Campo is nice but you can see it in minutes. There are some nice shops in the street just behind the upper part of the piazza (it slopes down).

Siena deserves a day--Assisi half a day. Neither are on your best route to Rome--Orvieto is.

Yes, Cristina...if you are covering all this ground in 11 days, you are going to have to get out a map and plot it pretty carefully.

If you have not driven in Italy before, IMHO, the drive from Florence to Rome with a nicely timed stop for lunch and look-see at Orvieto will be more than enough for one day...

To try to add either Siena (driving entry/parking nightmare) or Assisi (very full of tourists anytime) is just madness. They are truly off your path.