If you want to get your whole family into backpacking, you can do what we did with our kids, Jim and Ciera. When Jim was 6 and Ciera 11 we took them on their first overnight backpack, a 2 mile hike to Baker Lake near Ketchum. They carried their own packs, and we didn’t carry Jim once. His pack contained not much more than his lunch and a raincoat. I was carrying quite a load, including his sleeping bag. In those days we had traditional external frame backpacks, and a heavy tent.
We were a skiing family, so over the winter we skied. The next summer we did some easy hikes with now 7 year old Jim and 12 year old Ciera. We hiked to Norton lakes in the Smokey Mountains of Idaho, Bench lakes with another family with kids, Boulder Basin with several families, Bellas lake with some other families,and car camping near the harmonica festival being held near Yellow Pine.
The next year we had family trips to Sawtooth Lake, Boulder Lake in the Pioneers, Bench with another family and Washington lake with another family.
The next summer we did several trips, including Sawtooth Lake, and Washington Lake.
By then we fit in as many family backpacks as we had time, between soccer, swim team and visits to our parents in Colorado and Clearwater. A great one was when Jim was 10, older sister Laura was 24, and Ciera was 15. That trip was to Kane Lake.
All I can say is those years are brief, so backpack with the kids while they can stand you.