Are you looking for just a one day outing? Or longer?
You might contact http://www.cicloposse.com/ They do shorter tours. Giuliana might be able to do a custom tour for the 4 of you for a day, rental bikes, etc and a short route without a guide- or you can find a day tour with a guide if they have one scheduled at the time you are in Italy.
I agree with Frank. You will not find a tour of 10 miles. In biking terms...that is nothing. Most days on a bike tour cover 25+ miles...most in the mid 30 mile range, based on the terrain. Most of the hilltop towns are at least 20 miles apart.
Also...the hills of Tuscany are not easy riding, but I'm sure they could find you a fairly flat route.
If you plan to bike in Italy...please don't just "show up" to ride, you do need to train by riding some hills and longer distances. 10 miles might sound like a long distance to you, but it's really not in bike riding terms!
We've done 2 self guided tours with Cicloposse and are very happy to recommend them as excellent!
Feel free to send me a private email if you have more questions. We've done about 5 bike tours in Italy and can let you know what to expect.