Essaouira is usually the first day trip an operator adds to a Marrakech week, and for good reason: it changes the register of the programme completely, from inland city to Atlantic coast. It is also the day where the itinerary most often accounts for the road and nothing else.
The operational questions are all at the destination. Where does the coach actually stop, how far is the group from there to where the day begins, and does that walk work for everyone on the vehicle? A group that includes people who cannot manage an extended walk on uneven ground has a different version of this day, and the time to establish that is when the programme is built rather than when forty people are standing beside a coach.
Timing is the second thing. A day trip that leaves late arrives with less usable time than the itinerary suggests, and the return is rarely planned with the same care as the outward leg. We plan the return as its own movement, with a departure time that reflects what the group will actually be doing rather than an optimistic pickup.
Then there is wind. It is a coastal town; wind is the normal condition rather than the exception, and it is the thing that undoes outdoor arrangements. A seated lunch outdoors, a staged activity on the beach, anything freestanding — each needs an indoor version planned at the same time, not improvised when the day arrives.
Finally, the honest question of whether the day belongs in the programme at all. A day trip here costs a meaningful share of the day in transit, and for a group that has already had two early starts it can be the point where a good week becomes a tiring one. An overnight changes the whole character of the visit. We will say so when we think it is the better answer for your client, even though the day trip is the simpler thing for us to operate.