1. A method of planning deployment of optical network elements (ONEs), the method comprising: initializing models of ONEs within a topology of ONEs with a model of an amplifier with amplification and noise characteristics compatible with respective ONEs; computing an optical signal-to-noise ratio (OSNR) margin table as a function of the topology and model of amplification and noise characteristics, negative OSNR margins in the OSNR margin table representing optical regenerations within the topology; iteratively replacing the models of amplifiers with models of different amplifiers with corresponding amplification and noise characteristics within at least a subset of the models of ONEs and recomputing the OSNR margin table in an attempt to reduce the number of negative OSNR margins within the OSNR margin table to reduce the corresponding optical regenerations within the topology; and reporting indications of amplifiers represented by the models of amplifiers after a given number of iterations.