Depends on the size of the club, layout, flooring type and how sh***y it gets at the end of a night. For example, if they have carpeted floor and sell food then you would need to charge more than if it was altro floor and they didn't sell food, as in the first instance you would be cleaning carpets and in the second you could get by with mopping.
Also you would need to find out whether they are open in the day as well as this would mean that cleaning would need to be done at very unsociable hours.