The first thing that comes to mind when I think about families is the "The Family: A Proclamation to the World" put out by the church. It is a great guide on the importance of families, which is what this FHE idea is all about.
This FHE idea about families is good for kids of all ages, and even adults.
FHE Theme: The Importance of Families
Scripture: Mosiah 4:14-15
Songs: "Love at Home" LDS Hymnbook, "Families Can be Together Forever" Children's Songbook
Story: Tell your own family's story. How you and your spouse met, or how your parents met. Tell how you felt when each of the children were born. Give an example of how much you love a sibling, parent, cousin, grandmother, etc. Mention a time when you were happy to be a part of a family. End with how important having a strong and eternal family is to you.
Now read the "The Family: A Proclamation to the World" out loud. If you don't have a copy of it, you can find it on the LDS church website here. Even if you are without children, in a large family, without a spouse, or a great grandparent - it doesn't matter your circumstances because you are always a part of a family, and the Proclamation to the Family is important for all of us.
If you have younger kids who don't quite understand the Proclamation to the Family, I suggest our Proclamation Primary Talk. It puts things into terms that kids can understand, it doesn't take long to read (so short attention spans are ok), and you can include a picture of your own family.
Encourage discussion on how important family is - let each person tell stories and voice positive opinions. Ask and answer questions.
Then end the FHE by watching this great video from the Mormon Channel. It will really get everyone thinking about families and how grateful they are to be a part of one. Plus, it will end things in a happy peaceful way.