14 days in villa outside Florence. Need suggestions for day trips

How many people are you trying to move at one time?
Will you have several cars, or are looking for tour companies that have buses?

Several cars/ vans. Not really interested in tour groups. We are 8 adults and 8 children

It might be smart to break into smaller groups so that everyone gets to see things they're interested in. Then, reconvene at dinner and compare your days. It's a little easier to manage transportation in that case and you have enough days that people can rotate their traveling companions and spend time with everyone. This also allows for people to have a down day at the villa and relax while not forcing a rest day on everyone at once

When you say "outside Florence," can you be more specific? Which compass direction from Florence and about how far outside? Your base's location will help us tell which day trips are practical and if there are any hidden gems right in your backyard.

We are staying near Cerbaia which is south west of the center of Florence not far from San Cassiano which is east of us.

I don't know that area and can't help with day trips, but one thing you might consider is hiring a chef to come out to the villa and prepare dinner for you once or twice. You might even be able to find someone who'd do a combination cooking class (for the interested parties--I doubt your kitchen would hold 17 people at once) and dinner. The person you're renting from might be able to suggest someone who does this.