A demand-side platform (DSP) may bid on advertising opportunities (e.g., provided by a supply-side platform (SSP)) on behalf of an advertiser wishing to place an advertisement, such as part of an advertisement campaign. A target advertisement may be selected based upon various criteria, and a bid for the target advertisement to run during the advertising opportunity is made in a manner that satisfies one or more goals of the advertisement campaign while also being beneficial to the DSP. For example, the target advertisement may be selected from a reduced problem space where merely advertisements corresponding to a target advertising opportunity class are evaluated, where the target opportunity class corresponds to an opportunity class of the advertising opportunity. Win rate modeling data, inventory cost modeling data, user response modeling data, and/or other information may be used to select the target advertisement.