I haven't done this tour, but it really depends on your family and their interests. Cinque Terre can be very crowded at many times of year, and it is definitely no longer a quiet unknown place. Depending on when you are going it may not be the most fun, but it is a beautiful location. RS tours generally only stay in centrally located hotels. The tour itinerary tells you what you would do in Volterra:
This morning, we'll take a walking tour with a local guide who'll make
Volterra's traditions and history come alive. We'll also visit an
alabaster workshop and tour the Guarnacci Etruscan Museum, one of
Italy's best places to learn about this mysterious pre-Roman
civilization. Then you'll have time to poke around the ancient lanes
on your own. We'll regroup later this afternoon to learn about and
taste some of the region's famous wines, followed by dinner on your
own.
I see you've asked about several other tour options, did none of those suit you? Have you considered the family tour which does cater to younger folks and includes Florence (but not Rome)?