Americans' rhymes with:
american's, transamerican's, american's, transamerican's, american's, transamerican's, american's, transamerican's, american's, dominicans, mexicans, new-mexicans, pelican's, pelicans, republican's, republicans, republicans', transamerican's, vatican's
Americans' sounds like:
american's, americana's, americanas, americanize, americanos, americans