This was one of the real highlights of my trip to Morocco. The desert is absolutely awe-inspiring, and you can't quite believe your eyes. The dunes seem to glow and change colour throughout the day with the sunlight. You can't understand how incredible the sight is unless you see it yourself! We travelled by bus from Fes to Rissani, which is the end of the road before you hit the dunes of the desert.
Merzouga is actually a few kilometers south, with all the hotels situated in a line along the edge of the sand. Luckily, all the accommodation is reasonably far apart, so you keep the feeling of isolation that you so want from the desert. You should organise your hotel in advance, as they'll helpfully come and pick you up from Rissani. Alternatively, you can always get a grand taxi or hitchhike your way into the desert, but these will cost you money, whilst the hotels will take you for free. Of course, you can always get a hire car in one of the bigger cities, but bear in mind that smaller cars won't be able to cope with the sand and can easily get stuck.
We stayed at Auberge Yasmina, which was brilliant, with really excellent Berber food. The hotel sits right next to a lake, which was dry when we were there, but it's a real sight in the spring, when it's full of water and wildlife. Since we were on a budget, we opted to sleep on the hotel's roof. Although this isn't exactly the luxury option, it was perfect for us, as it meant that we actually got a nice COOL night's sleep!!
All the hotels will organise camel treks for you, but you may have to bargain hard for a price if you're watching your money. You should be offered the option of taking a shorter trek if you prefer, or like we did, an overnight trek. We trekked for a couple of hours to see the sunset and then continued onto a traditional Berber encampment where we stayed for the night. We ate huge tagines, listened to gnawa drums, and slept under the stars--the sky out there is just as amazing as the desert itself. In the morning we watched the sun rise from the top of a dune and then trekked the couple of hours back to the hotel for breakfast. It was such a unique and unforgettable experience; I really can't recommend it highly enough!
I have one tip, though: when choosing your camel, choose one with a SMALL hump!! You sit behind the hump, and needless to say, this can be particularly painful for men, especially when going up and down the dunes. Camels aren't the most comfortable animals to ride at the best of times, so you might as well try and make the experience as pleasant as possible for yourself!
Lots of companies in Marrakesh organise 3-day excursions out to Merzouga. These are real whirlwind tours, as it's a hugely long way from Marrakesh to the desert--don't underestimate the size of Morocco! These are a good way to see the Sahara if time is an issue, but the tour group that came on the trek with us literally got straight off the bus and onto the camels and the next morning got straight off the camels and onto the bus again.
We stayed in the desert for 2 days and got the chance to truly appreciate the landscape and the lives of the people who live in such a hostile environment. It also offered us the chance for peace and a total time out from the frenetic pace of life we all have to endure, a very rare opportunity in this day and age. Take a good book, a pack of cards, and your postcards to write and you'll have a very happy, if hot, couple of days!