What will your transport be in France?
We got to decent sized wheely cases and two med sized ones. Get straps and piggy back the med one onto the bigger one.
BUT we weren't away in the summer so had jeans jumpers jackets and all that too. Check about bedding!
Take enough clothes for a week, accept you will spend one day at the laundry room and accept your kids might be a bit manky and you could take two cases only.
Packpack each for the kids to carry on with all stuff to amuse them on board.