Marrakech
The most modern airport, enough to do for a week on your first trip, very cosmopolitan, pretty safe (they even have a specific tourist police division) and more hotels than you can shake a very very large stick at.
Hotels from the cheapest to the most luxurious, small family run to bland western chains (Ibis etc) and everything inbetween.
Mountains 40 miles to the south, Hamada to the north east (dry stony desert) and perfect weather in April (though cooler than you might imagine)
Lots of car hire places if you want to get up the mountains, but pplenty to do within walking distances of most hotels.
Soukh, tanneries, the biggest al-fresco restaurant area in the world in the square at night (which is a world heritage site) and a good if bustling introduction to Morocco.
You can even eat at McDonalds, Pizza hut or KFC if you really want to, but it would be a shame to sink so low.