Morocco is an extremely large and diversified country- from beaches on the Atlantic and Mediterranean via high mountainous regions( medium and high-Atlas..),dessert zones,imperial cities ,tourist-traps -you name it -all is here !
If you have say two weeks- I'd absolutely spend five days touring the most important "Villes Imperiales" like Marrakech,Fez,Meknes,Rabat or Tétuan.
Casablanca is interesting but not the most important tourist attraction( but the business capital of the country )
I'd definitely spend two-to three days in Marrekech ,but be aware that the city is very "trendy" with all the negatives that comprises.(Tourist-ripp-off's,pocket thieves..) but despite that a marvellous atmoshpere of history,smells (the famous "Place Jemâa el Fna" with all it's folklorist stands..) the "souk" or covered market ( you have to bargain at least 35%..) -the famous old palces,mosques-weel three days will be quickly over..
Then rent a car and drive one of the most sceenic routes on earth from Marrakech via the Atlas mountains to Ouarzazate and the Drâa valley- un unforgettable trip over kasbah-villages ,mountain-roads,olive-yards and wadi's 'dried river beds..)
The area of Ouarzazate is the theater of many movie-shootings (Lawrance of Arabia..)
Prior to that you should visit Fez (very beautiful old medina..) and /or Rabat but also the Atlantic port of Essaouira have been used for many film-back-stages..
Please respect animals - don't eat them...