You should not leave Granada if you haven´t seen the Carthusian Monastery, which is a jewel of the Spanish Baroque, and the old arab district Albaicin, enclosing within its medieval walls churches, convents, cisterns, palaces... and of course the balcony of St. Nicholas, and its famous view of the sunset in front of the Alhambra and the Sierra Nevada mountains...always in the atmosfhere of the old islamic area. The Albaicin has been recently scheduled by the UNESCO as a Cultural World Heritage.
As this is a private tour, you pay for the service itself not per person, so thirty people would pay like one.