Wow - seriously impressed - and no arguments, strops or disagreements 
No arguments are listened to. I sail blithely on towards the holiday.
They know where we are going, what the likely daily itinerary will be and what sort of things we do on holiday.
They have been informed of the accommodation standards and limits.
Time of departure is set in stone.
Each person is issued with one crate

That will contain the clothes they wish to take ~ there is no leeway.
Lap-tops travel in the car. A sixth crate will contain towels etc. Loose coats/anoraks go on back shelf.
Cameras go in the space beneath the driver's seat along with telescopic fishing rods x2, binoculars and hi-viz vest.
Food for consumption en route goes in the air conditioned glove box or in the storage spaces in the doors. First aid kit is in floor compartment beneath THW's feet. Fishing bag is in similar stowage beneath Minor's feet.
What they fail to take they can do without for a week.