We show that a ranking model produced by machine learning outperforms two baselines when applied to the task of selecting texts for use in creating a unit-selection synthesis voice with good domain coverage. The model learns to predict the estimated utility of an utterance based on features relating it to the utterances selected so far and a corpus of target utterances. Our analyses indicate that our discriminative approach continues to work well even though the presence of rich prosodic and nonprosodic features significantly expands the search space beyond what has previously been handled by greedy methods. Index Terms: speech synthesis, unit selection, machine learning