Best solution is a proper padded bike bag and to dissassemble the bike as much as possible and carefully pack each part with pipe insulation and bubble wrap/rags, wind the derailleurs in and put in fork spacers front and back and wedges between the brake pads.
When trekking, I dismantle it, lash it together with cable ties and put it in massive heavy duty plastic bag – but my trekking bike is far from cosmetically pristine.
If you do use a box, pack it with all your biking clothes for extra padding.
Some airlines treat bikes as ‘sporting equipment’ and charge extra irrespective of whether they might fit in your luggage allowance or not, which is another good reason to bung them in a bike bag as they look more innocuous that way.
PS I’ve flown with my bike into Marrakech before and there is no oversize luggage counter on the way out and they insisted on putting it on the belt with my bags. Check on arrival about this and make sure you know where you have to take it on departure.
PPS: You can buy booze at the Carrefour on the edge of Marrakech and nowhere else – we drew many jealous glances from our fellow guests on the hotel terrace when we produced 3 bottles of Bourdeaux to go with dinner.