Marrakesh lies about 350Km from Agadir. If you have time to take a trip to Marrakesh, then do a two day trip (or longer). People do offer a 1 day trip but you will miss the best parts - the night life in the Main Square, so we recommend a longer visit.
When you arrive in Marrakesh, immediately you will feel the vibe of this lively city - especially compared to Agadir or Essaouria!
Go to the Souk and wander around the labyrinth of alley ways and stalls, if you can't find it in Marrakesh it doesn't exist! Then go to the Main Square or Djemaa el Fna in the old city. Here you will find snake charmers, acrobats, magicians, jugglers and all manner of entertainment - be careful of your camera a sneaked shot will cost you money, they are eagle-eyed to catch you!
Enjoy a tea on the roof terrace overlooking the Square and take a look around the Mosque, and await the sun to go down.
Then Djemmaa elFna really transforms into a mass of food stalls where you can eat just about anything you like for a few pounds. Don't worry too much about food poisoning as all the food is prepared and cooked in front of you - and you will join hundreds of locals doing exactly the same - this is real Morocco.
As darkness descends, the Square fills with story tellers, healers, musical instruments...then the beats and vibes of Marrakesh take over!
Whilst the hustle and bustle can be intimidating, generally, you will very safe, but do be aware of the children. They bump into you and "hug" you, mostly with a view to robbing you. Just be firm with the command "Laa" (no) and smile. There are plenty of police patrolling the area so if you do get hassled, just go near one and the children will run away. It is best not to give money to anybody begging as well.