The traveler’s Mecca in 60s-70s, Morocco is still a fascinating mix of Islamic, Arab, African, and Berber cultures with a topping of France. Throw in some pleasant cities, eye-boggling landscapes, colorful people, excellent beaches, good trekking, plenty of interesting shopping and there's something for everyone. Moroccans are mostly Muslim but not too obsessive about it, flights from the UK take no more than 3 hours and the time difference is negligible. Flights now go conveniently to Marrakesh as well as Casablanca.

Downsides:

Although local people are friendly, it sometimes seems that every male over 7 years old wants to be either your guide or take you to his brother's shop. Some salesmen can be aggressive. Speaking French is not essential, but extremely useful. There are many great places out of the way for which you will need to hire a taxi or arrange your own transport.

Morocco's main attractions:Marrakesh [aka Marrakech]

offers some terrific buildings - especially traditional riads, good museums and a great covered souk [market] - the best place to find good quality crafts in Morocco - but most of all Marrakech hosts Djemaa el Fna, the wackiest square in Morocco, where assorted weirdoes put on performances and in the evening food stalls serve excellent local cuisine.

Fès

is the oldest imperial city in Morocco and has the largest medina [old city] and souks in the world, with great old walls and gates. You have to get lost in this medieval maze of 10,000 tiny streets to feel the city. Another fine old city - Meknes, is a good day trip from Fès.

Sahara Dunes.

Travel past Erfoud [to Merzouga] or Zagora [to M'Hamid] to get to the dunes at the edge of the Sahara desert, and stay two or three days or more to get a real feel for the place. Drive the lovely Ziz Valley from Errachidia to Erfoud - then on to Merzouga and the Sahara desert. Or along the Dràa Valley from Ouarzazate to Zagora and on into the desert. Also driving between Errachidia and Ouarzazate [the Kasbah Route] with snow-capped mountains, valleys, oases, villages and Kasbahs is magnificent. Visit the Todra and Dadès gorges.

The Atlas Mountains.

Driving Errachidia - Marrakech through/beside the mountains is highly recommended; navigation is fairly easy, the roads are uncrowned and views spectacular.

Essaouria.

For a cool seaside scene try this pretty blue-and-white walled fishing port, rather than the over packaged Agadir. It's relaxed but authentic and fronts a large, firm brown beach that is less than great for sunbathers and other inactive beach-goers due to a pretty constant N EAST wind, but much favored by windsurfers, kite surfers, sand-yachters and quad bikers. Get there via a spectacular road in a couple of hours from Marrakesh.
 

Casablanca

is a huge modern city with not much ethnic interest bar the biggest mosque in the world and the old quarter.

Rabat,

the capital and seat of government, is smaller than Casablanca and much more traveler-friendly though still not a must-see. It's relaxed, hassle-free, has some worthy sights, fine architecture and masses of pleasant cafés.

Tangier,

Morocco's main port and only an hour by ferry from Spain has a some interesting structures, a couple of not-very-clean beaches and a run-down old town but is useful as a transit point to the magic of the rest of Morocco. 

The Sahara Desert:

This notorious desert stretching across North Africa is the size of the USA but only about 25% sand. The rest is composed of volcanic hills, rock and gravel plains and some vegetation which is home to around 300 species of bird and animals such as mongooses, snakes, jackals, hares, deer, foxes and even baboons. Desert experiences are not to be missed, though preferably on camel back and for a couple of days, including sleeping under the stars.