Cinque Terre is less than an hour away from Camp Darby if I remember correctly, you could make that your base and then drive up. When you get there, park your car along the road like everyone else and mark the spot on your GPS. Walk down and buy a train pass, because you can walk to each town, but at least one is less strenuous if you just take the train.
While you're up there you can also take the kids to Collodi, the town of Pinocchio, Lucca, with its wall around the town you can walk, or to the marble quarry in Carrara.
There is a very good book called "Italy with Kids" that we used to have that talks about all the towns you can travel to that the kids may find interesting, right down to good places to stay and where to get the best gelato in town. My sponsor gave it to me and I've passed it on, but you can find it at Amazon.