A few days before we leave, I'll drag all our suitcases to the driveway and "pack" the trunk to determine which bags to use & which to leave at home. I'll then drag those into the Living Room and instruct DW that "these are the bags we're using. Do NOT put anything in ANY additional bags". 2 days before we leave, I lay out my clothes for the trip. The day before, DW packs all the bags. That night, I will arrive home from work to find she's used bags not on my "approved" list, and those will need to be undone (We have a compact car. It really is important we use the bags that FIT). Everything but the cooler, toiletry bag, and electronics bag go in the car the night before we leave.