I have a holiday packing list saved in Word that I update every year. My original one mentioned Pampers and armbands for DS, subsequent years don't. It's sweet seeing the changes over the years!
Anyway, my list comprises:
Travel Documents & Electronics: Passports x 3, Flight tickets book/printouts, Cash (Euros), Travel Insurance docs, Global Health Insurance cards, car park voucher airport, car hire documents, Driving Licence, chargers, phones, etc etc.
Sundries: which would be books, pool toys, teabags, plastic bags for dirty laundry, scissors, multivitamins, holiday purse, etc.
Outdoors: Sun hats, sunglasses, sunscreen, insect repellent, hamam towels, sliders/swim shoes, beach bag, etc.
The Kid: T-shirts x 10, shorts x loads, pants x whatever, swimmers x 2, trainers/joggers/long sleeve top (for the plane), socks, PJ bottoms, sandals etc.
Toiletries & Meds: Toothpaste, Calpol, Audisol spray, Anthisan cream (bites & stings), shampoo, toilet bag with nail scissors, tweezers etc, hairbrush, contact lens stuff, any medicines, etc etc.
Obviously not an exhaustive list (it's staggering how much is on mine!
) but I recommend you have one of your own. The second page has details on it about what worked and what didn't, where things are stored, the dates on our passports and the latest they'd need to be renewed, sizes of cabin bags, things I need to do the day before we fly, all useful information like that.
When we come back I update the list and make a note of anything significant, like one year my suitcase got ripped so I made a note to get a replacement before we next travelled. I would never remember from one year to another and would get caught out in July needing a new suitcase at the busiest time of year...