Start with one shared source of truth
The hardest part of planning a group trip is rarely choosing a city. The hard part is keeping everyone aligned after the plan changes. A restaurant moves to another night, one person books a later flight, the rental car pickup time changes, and suddenly the group chat has three versions of the same weekend.
Your template should prevent that drift. Put every confirmed detail in one place and make it clear which items are still tentative. That keeps people from relying on screenshots, old messages, or separate notes that stop matching the current plan.
Use a simple structure: trip overview, traveler list, arrivals and departures, lodging, day-by-day schedule, reservations, budget notes, packing reminders, and backup options. The goal is not to document everything forever. The goal is to make the next decision obvious when someone asks what is happening today.