How does this sound for an itinerary in mid September?
Fly to Venice, arrive late night unfortunately, but hotel is on Grand Canal
3 nights Venice
train to Florence, 2 nights Florence
Drive from Florence to farm outside of San Gimignano, stay 6 nights on farm
Drive to Umbria, stay on farm south of Perugia for 4 nights
Drive to Orvieto, leave car there and train to Rome (or drop car off in Rome?)
3 nights Rome, fly home from Rome

While in Tuscany/Umbria we plan to visit some hill towns, chill out and get rested up for Rome. Does this sound like a nice mix?

This is perhaps the most perfect itinerary for the amount of time you have that I have ever seen posted here! I'm not one for staying on farms, but obviously you are -- and the time allowances, mix, and balance for each stop couldn't be more perfect in my opinion.

I agree with Patrick, sounds perfect!
Have a great time and report back!

Dear Colleen:

The only change I would make would be to add another day or two to Rome. Otherwise, sounds great!!!

Michelle

I agree with Michelle and say add another night or two in Rome. Perhaps you can cut this time off of your San Gimignano stay.
I guess it depends on your preferences. While the hill towns are absolutely wonderful, I personally wouldn't spend 10 days there to shortchange Rome which has so much to see. Then again, I also didn't find Rome as hectic as some have described.
I also went to Italy in mid-september (last year). Such great weather, and your itinerary sounds great! Wish I was going again...

having spent a week in san g. recently, i would agree with the other posters to spend more time in rome....san g is nice but limited...the town itself is worth visiting, early in the day or later in the day, after 5, ONCE and then move on....easy to get about outside of the town....we stayed on a mini-farm in the vineyards and it was quite pleasant and we found plenty to do but i think you have alotted too much time to this area....give rome an extra day or two...