In reply to mypyrex:
I use them quite regularly but they don't offer as good a deal as airmiles used to on flights since you now have to pay taxes, fees etc. For example I was looking at flights to the US in the summer, without avios it is £750 but using 40000 avios miles brings the price down to £450. In effect you are selling 40 000 avoid miles for £300 which isn't a great deal.
Conversely I used them last year for hotels and hire cars and the deals were infinitely better. For example I used 8000 miles to book four nights in a hotel in Florida, worth about £400 and I think that's pretty good.
Is it worth having a look at using you Avios for your hotel in Marrakech rather than the flights?