What to see
You are not sure where to go? These are the best places in Morocco…

Unesco World Heritage sites in Morocco:
Medina of Fes (1981)
Medina of Marrakech (1985)
Ksar of Ait-Benhaddou (1987)
Historic City of Meknes (1996)
Archaeological Site of Volubilis (1997)
Medina of Tétouan (formerly known as Titawin) (1997)
Medina of Essaouira (formerly Mogador) (2001)
Portuguese City of Mazagan (El Jadida) (2004)
Rabat, Modern Capital and Historic City: a Shared Heritage (2012)
Must see:
Marrakech Medina: Koutoubia mosque, Djemaa el-Fna, Medersa Ben Youssef
Fes Medina: Tanneries, Souks, Kairaoiune Mosque

The Sahara Desert
The High Atlas Mountains
Essaouira Medina
Casablanca: Hassan II Mosque
Should see:
Meknes Medina
Ait Benhaddou Kasbah
Volubilis (Roman ruins)
Rabat: Kasbah des Oudayas, Chellah Necropolis
Anti Atlas Mountains
Middle Atlas Mountains

If you have time:
Chefchaouen
Tétouan
Ziz Valley Oasis
Ifrane
Rif Mountains
Source: Unesco World Heritage Convention, own data