A group of us will be traveling in Italy in a couple of months, and as part of that trip we'll be staying at a villa in Tuscany in the San Gimignano area. We'll have a couple of rental cars, but for fun we're considering to rent mopeds (motor scooters) one day. Is that a good idea? Is it feasible? Where can we rent them from?
The first question is are you experienced motorcycle riders? Italy is not a good place to learn. Second to you have a motorcycle endorsement on your driver's license and the international driver's permit? See RoninRome for a discussion of motorcycling riding in Italy.
http://www.bellinibruno.com
I'm sure they know the requirements for foreigners in terms of licensing.
The more important issue is whether you have ever driven a motorcycle before.
Up to 125cc you do not need a motorcycle license but definitely get the Intl Drivers License
Definitely have travel medical insurance
Here are a couple of other resources:
This company has a good FAQ
Here is RoninRome's page about renting Vespas - it's a good read!