Essaouira is a 2,5 hr drive from Marrakesh Airport and a 3 hr drive from Agadir Airport. Both cities have direct connections with major European cities offered by several airlines:
air france / klm    iberia
easyjet    ryanair
atlas-blue    thomson fly
transavia    air berlin   

Moreover, Essaouira Airport can directly be reached from Paris or Casablanca by Royal Air Maroc.
We can arrange a taxi to collect you at Marrakech AP or Agadir
AP (around 600 DH/55 Euro), or you can take a Supratours bus.