Maybe Travel is a better topic but...
I always write a list for each person (yes I do all the packing, downtrodden wench that I am) and then pack by going through the list and ticking off each item as it goes into the suitcase. Basics on my list for a general summer holiday abroad in the EU are generally:
Hand luggage
Passport
EHIC
Travel insurance helpline number and policy number
Book
Tissues
Mobile, fully charged
Keys
Purse
Wet wipes
Sandwich/snack
Paracaetemol
Mints
Sunglasses
Camera
Liquids bag: lip balm, hand sanitiser, mini hand cream, mini sun cream
Hold bag
Photocopy of passport, EHIC and travel insurance details
Top x # of days + 1
Jeans
Trousers
Shorts x 3
Pants x # of days
Bra x half the # of days
Socks x half the # of days
Swimming costume
Towel
Flip-flops
Trainers/walking shoes
Jumper/cardigan
Hat
Hairbrush
Shampoo
Conditioner
Shower gel
Suncream
Insect repellent
Face wash
Moisturiser
Toothbrush
Toothpaste
Mini first aid kit
If I was going for a week or more then I would take my mobile charger and travel adaptor.
What your DC need depends on their ages.
Honestly though, if you aren?t going to the middle of nowhere then the only things you must absolutely not forget are your travel documents and your purse. Anything else can be easily bought at the destination.