Two bookings, one week, one small child: a resort where the whole day happens inside the gate, or a flat in the middle of a city where it happens outside. I make that choice from the walking map rather than the photographs, because the week gets decided by distances of five to fifteen minutes and by where everyone eats at six in the evening. Everything below follows from that one comparison.
Start from the walking map

What fails first in a city is the distance between the room and the nearest place that serves food at short notice, which turns a tired evening into a search. What fails first in a resort is day three, when the pool, the buffet and the same four corridors stop being enough for a child who wants a street. Put both failures on the table before you compare a single price.
I measure three routes on the map before I hold anything: room to food, room to shade or green space, and room to the nearest shop or pharmacy. In a city I want all three inside ten minutes on foot, and in a resort I want the shop and the medical point inside the gate instead of a shuttle ride away.
Getting there: the first ninety minutes
After a flight, a small child has roughly ninety minutes of goodwill, and the transfer decides where it gets spent. A resort usually absorbs that with a short drive and a check-in that happens while the bags go ahead to the room, whereas a city arrival often means a walk from the station with a pram, a lift that may not exist, and stairs nobody mentioned. So I book the arrival on purpose rather than by default.
- Resort: a private transfer, with gate to room under fifteen minutes once the bags move.
- City: a taxi to the door of the flat, then public transport from day two onwards.
- Both: nothing at all booked before noon on the first day.
Days built around one anchor
One booked thing before lunch keeps the day structured and leaves the afternoon free for the nap that everyone needs and nobody wants to admit to. A resort makes that easy, because the anchor can be a boat trip or a session in the kids club that costs nothing extra. A city makes it harder, since the same anchor involves a walk, a queue and a closing time that does not move.
I keep the nap in the room rather than in the buggy. A child who sleeps on the move tends to wake at the worst possible moment, usually in the middle of the thing you paid for, and the day then splits into two halves that nobody enjoys.
Rooms, beds and the bathroom queue
The layout decides the morning: a second bathroom or at least a second shower, a door that actually closes, and a bed a child can be moved out of without waking the adults. I take a family room with a separate sleeping corner rather than a double pushed against a wall, because at two in the morning the gap between the beds matters far more than the category on the booking.
In a city flat I ask for the floor and the lift in writing, and I confirm whether the pram fits through the stairwell if it does not. In a resort I ask whether the room sits more than a five-minute walk from the restaurant, because that walk at the end of a long day is the detail families underestimate every time.
Eating at six in the evening
Small children eat early, and after a travel day I would rather eat early with them than negotiate a nine o'clock table. A resort has dinner service that opens at six and runs late enough to cover both schedules, while a city needs either a booked table or a kitchen, and that kitchen is the main reason I take a flat for a week with a fussy eater. I check one thing before booking either: how far the room is from somewhere that will still serve food when the day goes wrong.
The trade is worth naming plainly. A resort buys you service and convenience and gives up the street, the bakery and the walk home after dinner; a city gives you all three and asks for a reservation, a route and a little more stamina in the afternoon.
Before you put down a deposit, fix the arrival day first: the transfer, the room, and one meal that needs no decision at six. The option that makes those three effortless is usually the base that will not need rescuing on day four.