Definitely do the day excursion to the Ouzoud waterfalls if you have time. Great little escape from the heat and busy Marrakech. There is a waterpark in Marrakech and lovely gardens. I feel that Marrakech is like an intro to India, you get the haggling and a little bit of culture but for the most part, it seems very kitschy.
Insider Tip:20 dirhan to get to the bus station from the main square. If you are lost, go to the police station and someone will help you and you don't have to tip. If a random stranger offers to help, expect them to ask you for money at the end.