Marrakech is fascinating with the Djemma el fna square with its acrobats and monkeys and snake charmers but a full week may have a fairly high heat and hassle factor.
There are some great day trip options especially the Atlas Mountains.
I would consider a two centre holiday ending on the coast. Agadir would probably be better for resort style attractions but Essaouira is an atmospheric, white-washed walled town with sandy beaches a 10 minute stroll out of town, windsurfing and horse or camel riding out to Jimi Hendrix's "castles made of sand"
Choices, choices.
Sounds brilliant RedRag