The multi-facility generalization of the Weber problem is used as a point of departure from which to examine a number of conceptual issues of location-allocation models. The restrictive assumption that consumers are allocated to their nearest facility is relaxed; an alternative formulation incorporating a spatial interaction model is outlined. Furthermore, it is argued that perfectly inelastic demand formulations should also be extended, because effected consumer utilization is directly dependent on the pattern of facilities, particularly the distance consumers have to travel to reach the facilities. The final characteristic of static models to be considered is multi-level formulations, and it is suggested that this could provide a means to develop dynamic models.