While yes, having the kids help with things does mean I have to be even more organized, it helps both of us. It may take me five minutes to write out a list for them, and five minutes or so of supervision, but if it would take me twenty minutes to complete the same task, then I am actually ahead of the game.
A packing list
An obvious way to have kids help is by having them help pack their own suitcase. We have color-coded, monogrammed duffel bags for every member of the family. I am red, my husband is black, Alfs is blue, Woody is purple and Sunshine is yellow. I can tell in a seconds whether we have all our bags in the car or wherever by the colors.
After distributing the bags, I provide the boys with a list that reads something like: 5 tshirts, 2 collared shirts, 6 pairs of shorts, 1 pair of pants, 10 pairs of socks, 10 pairs of underwear, 1 sweatshirt, 1 raincoat, 1 pair of sneakers, 1 pair of sandals, 1 hat, 1 swimsuit, and toiletries. I also give them some guidance as to what we need to be prepared for and let them at it. I do check through the clothing choices, but mostly it's up to them.
I also ask the boys to prepare some items for a personal backpack. They need a book and a couple of other small activities at the very least. I edit the backpack heavily as it seems to be the area the boys over-pack on.
Once that level of packing is done, I feel so much better about getting out the door.
An activity wish list
In addition to getting suitcases together, I also ask the boys to make lists of things they would really like to do or see on vacation, sometimes giving them the guidebooks to reference. While my husband and I have planned some overall activities and the itinerary, there is some room for wiggling, especially if there's something the kids would like to do and doing that something keeps the kids happier. It also makes them feel they have a say in the vacation - it's not mom and dad's vacation in which they tag along, but it really is a family vacation.
The final push to leave
In the last hours before we leave on a trip, when we are trying to get the house organized, the kids can be a great help in doing quick clean-ups, getting all the recycling down to the basement, finding this or that last minute thing we just remembered, or even just eating the last couple of things in the fridge. Again, the activity and participation helps manage their excitement. I often give each a final checklist that we go over while sitting in the driveway, and hopefully we won't have to go back into the house.
With everyone helping, we're less likely to forget something (though it seems like we always forget at least one thing), and more likely to be on with the fun of vacation more quickly.