So, yeah, been doing this for about 5 years now.
It started a way back when we had a trip with a loaded 3 row SUV, and not much space for luggage. I had a cargo carrier on my trailer hitch. Not sure of the weather, I though perhaps I will pick up a couple of the rubbermaid tubs. We loaded the clothes and some food items in the tubs. It worked great!
Today, most of our travel is car related. We pack differently depending on the situation.
A long weekend, with only 3 or 4 of us, we each have our own suitcase.
A week long trip when we will be making multiple hotel stops. When we do that, we tend to have one overnight bag with all the toiletries for everyone, and then one clothing bag per hotel. This way we do not have to unload everything every time.
We are DVC, so for those week long trips, we pack the tubs. The tubs are so easy, and quite frankly, less noticeable in the back of the SUV. They attract less attention when we stop for a meal or for some other reason. They are easy to bring up to the room They stack nicely when full, and they stack very nicely when empty. Once we arrive, we unpack the clothes, and whatever food we may have brought, and stack the bins in the closet, with plenty of room to spare. We do the same when we go to visit family.