Morocco, hands down. http://web2.flyertalk.com/forum/showthread.php?t=301347.

Someone mentioned Jordan; Petra, in southern Jordan (http://en.wikipedia.org/wiki/Petra%2C_Jordan) has to be seen to be believed. The town of Wadi Mousa, a short walk from Petra, has at least one decent hotel (I stayed at the Movenpick and it was quite nice.) Allow no less than one full day (stay 2 nights) though I've been told that you can spend 5 days there and not see anything twice.

Enjoy!