Money is where friend-group trips quietly go wrong: not big betrayals, but a hundred small ambiguities about who paid the taxi, the villa, the fifth round. Set the system before you fly.
One shared pot, one ledger
Each person pays in a fixed share at the start; one app tracks every shared cost. A single ledger beats a hundred settle-ups at dinner.
Split by capacity, not by head
Different incomes make equal splits feel unequal. Agree whether you are splitting evenly or by comfort level, and write it down before booking anything.
Name the luxury line early
One person's essential upgrade is another's waste. Decide which costs are shared (transport, lodging) and which are personal (spa, tasting menu).
A monthly checkout
Ten minutes every few nights to square the ledger prevents the end-of-trip reckoning that nobody enjoys.