Perks of taking the train from Casablanca to Marrakech
My timing was probably an added challenge, having visited during Ramadhan when train times were really unreliable.
Train schedules are really unreliable during Ramadhan, public holidays and generally throughout June when many people are visiting
Getting a seat is not really a challenge except during these days.
Most at times, you'll have to switch rains at Sidi Kacem( not all the times the train goes directly to Marrakech.)
On the brighter side
The train is really cheap and safe. Upgrading from one class to the next costs less than $10 and the most expensive tickets going for not more than 148 Dirhams. (Rates differ per season, check for the updated prices on ONCF website.)
For most international flights you're likely to land in Casablanca, there's a train station within the airport and you can board the train to Marrakech from there.