Wayne,
Try this company.
http://www.parkervillas.com/ My family got back in October from 3 weeks. Was the best trip ever. Rented a 9 passenger Opel van.
We stayed in the Zafferano apartment in San Gimignano, Siena (13th century tower re-modeled into ultra modern apartment).
An then in Il Giardino degli Ulivi - a private home in Poggio Mirteto, Rieti. About 45 minuets from Rome. It's on an olive orchard in a very private setting.
From San Gimignano, you can drive to Siena, Pisa, Luca, Firenze ect.
From Poggi Morteto we only went to Rome. Was a bit of a drive, but not too bad. And after a crazy days in Rome, it was nice to decompress in Poggi Mirteto.
Here a few pictures.
Check out the Parker Company. Excellent locations to choose from.
One of the views from our apartment in San Gimignano
One of the other views.
Home in Poggi Morteto
View from the home in Poggi Morteto
And you have to do this when in Pisa!
Feel free to email me with any questions.
-W