We stayed in a double room at the Hotel Kasbah Sahara Services. The room had a toilet and shower within the room (they also have rooms that use the clean, communal facilities instead). The rate included breakfast plus a delicious dinner (excluding drinks), and was a bargain. Not luxurious, but perfectly fine for a night. The free wi-fi is only accessible while in the manager's office but this wasn't a particular hardship. We were offered a free tour of M'hamid and the interesting kasbah with Musa (obviously it would be nice to tip your guide) after we'd settled in.
We left our rental car parked at the hotel while we went to Erg Chigaga the following day and night with Sahara Services. Mohammed was our guide, and unfortunately we weren't sure of our driver's name (it starts with an "A"...). They were both fantastic. The drive to Erg Chigaga was fun. On arrival at our tents we were served tea and peanuts, then later a good lunch. Our tent had a comfortable double bed and smaller bathroom tent attached. The shower didn't really work but we had decided beforehand to minimise water usage in the desert anyway, so had come prepared with wipes instead (you could always take the top off the water tank and have a bucket shower if you wished). There is also a camp toilet in the tent. We slept well, and kept warm - couldn't ask for more.
The dinner was great, we were sure the food had been brought in from M'hamid but were assured that there is actually a chef on-site who had prepared everything. Dinner was followed by music and singing from all the staff. I appreciated their efforts, considering they would have worked all day, but think some guests would have rather gone to bed. Perhaps just a couple of songs would be fine?
We were very happy with both the hotel, and tour provided by Sahara Services and would heartily recommend them for a wonderful experience at Erg Chigaga.