Packing for a group trip is a different problem from packing for yourself. You already know how to bring your own socks. What goes wrong on group trips is the shared stuff: four people bring a bluetooth speaker, nobody brings a corkscrew, and the one cooler in the house is the small one somebody grabbed as an afterthought.
So the useful thing isn't one long list. It's two lists, with names next to the first one.
This is the list that needs assigning. Everything on it should have exactly one person's name beside it before anyone leaves.
Every trip
Lake or beach house
Ski or snow
Camping or backcountry
International
This one doesn't need assigning. It needs sending, once, early, so nobody has to ask.
The failure mode is a group chat where everyone says "I can bring a cooler" and nobody confirms, so either four coolers arrive or none do.
Put the shared list somewhere everyone can see, assign a name to each line, and leave it visible. The rule that makes it work: if your name isn't on it, don't bring it, and if your name is on it, it's yours to remember.
A few things worth deciding alongside the list:
Who's buying what, and does it go on the tally? A $60 cooler bought for the trip is a trip expense and goes on the trip tally like anything else. Gear somebody already owns doesn't — they're lending it, not selling it. Worth saying out loud, because the person who brings their own $300 tent and the person who buys a $60 cooler are doing different things.
Who's doing the grocery run? One person, with a list the group adds to beforehand, beats five people buying overlapping food. Have them buy for the shared meals only and let people grab their own snacks.
What's getting rented there instead? Bikes, boards, chairs, car seats. Usually cheaper than flying with them and always less work. Decide early, because the good stuff books out.
Reliably doubled: bluetooth speakers, sunscreen, phone chargers, salt and pepper, olive oil, coffee. Harmless, except the speakers.
Reliably forgotten: a corkscrew, trash bags, dish soap, a decent knife, a power strip, hand towels, and any kind of light for the walk from the car to the door. None of these are expensive. All of them produce a trip to the store on the first evening, when nobody wants to go.
The genuinely costly ones: chargers for anything that isn't a phone — camera batteries, a CPAP, a watch. A second car key. Anyone's medication. These are the ones to check at the door rather than trust to a list.
Three questions, answered out loud:
That's it. Everything else you can buy there.
Shared household items a rental won't have — a power strip, trash bags, dish soap, a corkscrew, a decent knife — plus earplugs and an eye mask, which matter far more in a full house than they do in a hotel room. The personal list barely changes; the shared list is the one that's new.
Write the shared list first, assign one name to every line, and keep the list somewhere the whole group can see it. The rule that prevents both duplicates and gaps: if your name isn't on a line, don't bring it, and if it is, it's yours to remember.
If someone buys it for the trip, yes — it goes on the tally like groceries or gas. If they already owned it, no; they're lending it. Say which is which when the list gets assigned, so nobody's surprised at settle-up.
A corkscrew, trash bags, dish soap, a sharp knife, a power strip, and a flashlight for the walk from the car. All cheap, all guaranteed to cost somebody a store run on the first night.
Less than for a solo trip of the same length, because houses have laundry and groups share gear. Pack for the forecast plus one warm layer, one outfit for a nicer dinner, and shoes you've already broken in.