My husband and I share a case and each of the kids get a bag each. 1 x change bags with essentials in for easy access 1 x packback of toddler toys/books
We pack everyone in separate bags. Usually duffle bags because they can be squished in as opposed to more rigid suitcases.
One large case and everyone’s stuff divided into packing cubes
I usually pack my daughter’s stuff with mine in a duffel bag to save on space. My youngest boys share a bag as well If I only had two children, I’d pack their stuff together in one bag.
For a 5 day trip, my husband and I share a small case, and we use a shoe organiser for the kids - one outfit per pouch, pj's etc. It can then be hung up and my 4 year old can pick out his outfit (but ive already picked because it will be pants, socks, tshirt and trousers that go together) If in the car we just roll it up, if we were going abroad, it fits in a case.
We did 2 big suitcases. 1 adult + 1 child per suitcase :)