Lysias is a good way to learn to read Greek prose. (Actually, the attribution to Lysias of most of virtually all the speeches collected under his name, with the exception of No. 12, can't be verified, and there's considerable doubt.) The speeches are written in clear but not unsophisticated Attic Greek. They served as a model for Greeks learning to write good Greek for two millenia (and that accounts for their survival to the present). Also, with a good commentary (and a number of them are available at reasonable cost), you can absorb a lot of information about Athenian daily life, legal procedure, social norms, etc. around 400 BCE, and they give insight into the thinking of the Athenian man in the street. After Lysias, you can move on to Demosthenes and Thucydides. Lysias 1 is a particularly appealing speech because it involves sex and murder.
Some other uses of the future optative are mentioned in Smyth, but they are all instances of subordinate clauses in past time where a future indicative would be used in an independent clause.