Been twice, great place, we never bothered with guides in the souk, just wandered around ourselves, can be a bit daunting as you will be approached, but a firm no usually does the business.
We hired a car, if you, don't leave it parked on a side street near the souk, we left ours to look for a cashpoint, and it was broken into and the radio nicked, all about an hour after we picked it up, and we spent 2 hours sorting it with the police. In town its also mad with mopeds and donkeys, and neither bother which side of the road they are on (even on dual carriageways). Out of town though its fine, we have driven to Essouira on the coast, about 3 hours, and Ait Benhaddou (below), which is over the atlas mountains, which is fabulous drive, and a great place to visit, but it requires a full day. We also went up to the ski resort at Oukaimeden, an interesting drive, about an hour and half from Marrakech.
If you want a beer or wine with a meal then you need to eat in a more upmarket place, or a hotel, away from the main square. There are some in the souk but they aren't easy to find.
