Techniques for selecting electrode combinations for stimulation therapy include delivering stimulation via each of at least two electrode combination classes during a therapy evaluation period. A first one of the classes comprises one or more electrode combinations that include electrodes within one or two columns of an implantable array of electrodes. The array may include at least three electrode columns. A second one of the classes comprises one or more electrode combinations that include electrodes within at least three electrode columns of the implantable array of electrodes. A preferred one of the electrode combination classes for a patient, and/or a number of leads to implant within the patient, may by selected based on feedback collected from the patient during the therapy evaluation period.