An advertising server allocates advertising impressions to meet advertisers' demands for opportunities to run advertising, for example ad content inserted into Web pages for payment. Supplies of advertising impressions are paired by their characteristics with demands that the supplies could meet. For paired eligible supplies and demands, an ideal allocation is determined, between zero and a maximum. The ideal allocations for all pairs are the coordinates of a utopia point in multidimensional space, although meeting all these ideals is likely to be impossible because of practical constraints. Using optional weighting, candidate allocations are tested or compared. Each candidate allocation produces coordinates in the multidimensional space. The candidate allocations are compared, based on the relative proximity of their coordinates to the potentially-impossible utopia point in multidimensional space. A ranking is stored or the selected allocation is executed, under control of a programmed processor.