I think I liked the last method best. Our second trip in which we put everyone's clothes in separate labeled bags left us with what felt like a hundred bags all over the place. Our last trip we placed all the boys pants for one day in a bag together and their shirts in another bag, etc. This left us with less bags everywhere and the same accomplishment of being organized.
I do have to admit that this idea was not my own. I borrowed it from the Duggar's and it works. So the next time you're heading out on a trip try it and see what you think.