Short answer
A multi-generational Naples trip usually has 10-18 people spanning three or four generations. 5th Avenue South and 3rd Street South restaurants seat parties of 6 max in winter season and book 2-4 weeks ahead. For a group with grandparents and grandkids, a private chef at the rental is almost always the better call: no walk from a garage, no noise level that drowns out hearing aids, and the kids can be feral until food is up.