I've never been, but I want to go! I blame "Fodor's Morocco" for that. :-D Oh, and Bob Hope and Bing Crosby. ;-)
You can get the book ("Fodor's Morocco: The Guide for All Budgets") fairly cheap at Amazon...it's really cool.
Lonely Planet guides are always a good place to start. their info is most always pertinent, easy-to-read and hip.