A group of two decides what to do over breakfast. A group of six decides what to do the day after they could have got tickets.
This is the actual cost of travelling with friends, and it is not a money problem at first. Everything worth seeing in a European city now runs on timed entry, and timed entry is brutal to groups. Six adjacent slots at 10am on a Saturday do not exist three days out. Two slots do, at 9am and 4pm, which turns the day into a negotiation about who takes the early one.
The Alhambra sells out weeks ahead in season. The Anne Frank House only sells online, for a specific time. Sagrada Família will happily show you a calendar of grey squares. None of this is a scam invented to punish the disorganised; it is what happens when a building has a fire limit and the internet has everybody's attention. It just means the group that decides on Wednesday sees the thing on Friday at 8:30am or not at all.
Decide one thing before you go
You do not need an itinerary. You need one anchor per city: the single thing the group would be annoyed to miss. Book that before you leave, at the time that suits the slowest riser, and let everything else stay loose. Groups that try to book six activities in advance start fights in the planning chat. Groups that book none arrive and queue.
Who pays for six tickets
One card, obviously, because six people cannot check out simultaneously and hold adjacent seats. So one person spends €138 on museum tickets in March for a trip in June, and by June two things have happened: the group has forgotten, and one person is not coming.
Say the rule out loud when you buy: non refundable means you owe it whether you come or not. It sounds harsh in a group chat in March. It is much kinder than the alternative, which is the buyer quietly absorbing a no-show ticket because raising it feels petty. Put the expense in the ledger the day you buy it, with everyone's name on it, and the awkward conversation happens once, in advance, in writing, at a moment when nobody is upset.
For museums and attractions our partner is Tiqets, which suits groups because the tickets arrive on your phone straight away and can be forwarded one at a time.
Affiliate link: same price for you, a commission for Billy, which is what pays for the app instead of you paying for it.
The thing nobody books and everybody needs
Restaurants. A group of six walking into a good restaurant at 9pm without a table is a group eating at the second choice, and second choice is where trips get their worst meal and their most expensive round of drinks while waiting. Book the two dinners that matter.
I know how this reads: a piece about spontaneity that tells you to reserve everything. The honest version is that groups above four stopped being able to improvise somewhere around the time every ticket became a QR code with a time on it, and pretending otherwise costs the group its mornings. Two people can still wander into a city and let it happen. Six people wandering is a committee.