What range of heights are allowed for wall receptacles?
The NEC doesn't count a receptacle above 5-1/2' to satisfy the requirement - 

210.52(4) Located more than 1.7 m (51⁄2 ft) above the floor

The NEC doesn't have a lower limit for height, in fact 210.52(A)(3) allows floor receptacles within 18" of the wall to satisfy the requirement.  


  (3) Floor Receptacles. Receptacle outlets in floors shall
  not be counted as part of the required number of receptacle
  outlets unless located within 450 mm (18 in.) of the wall.


Now if there are any requirements for ADA accessibility, receptacles and switches must be between 15" and 48" and unobstructed.