We stayed at casa di sopra in Tuscany. Fabulous place. You'll need a car to get about but the villa is so lovely you might want to stay home a lot! It officially sleeps 12 but we were 7 and it was just the right amount of space. http://www.cvtravel.co.uk/en/destinations/europe/italy/tuscany/chianti--near-siena/accommodation/pages/casa-di-sopra.aspx
I stayed here last summer with another family and us (4 adults, 3 DC's)
Absolutely amazing property, totally secluded (electronic gated gravel drive to a closed off mountain villa) and the owner was wonderful. The photos don't do it justice.
There was plenty of space, the pool was huge and slightly below the property amongst the olive and fruit trees. It had 4 bathrooms, a small downstairs bedroom and four double bedrooms. The one we were in had it's own private sun terrace.
The owner made sure there were things for the kids (archery set, Harry Potter DVDs etc), the kitchen was well equipped and there was a lovely dining area under a gazebo for the evenings. We spent most of our time out there playing games and eating dinner.
Couldn't recommend it highly enough. You would need a car to explore, or to get to the supermarket and the local village (which had three nice pizzerias, a Gelateria, and the typical square where the locals came to cool off in the evening).
We would return again this year, but we have to travel to a wedding in the summer holidays.