David Decosimo of Loyola University in Baltimore has added his voice to the much-considered issue of Thomas's teaching on the virtue of the pagans. His book, Ethics as a Work of Charity: Thomas Aquinas and Pagan Virtue, has been published by Stanford University Press, who has a fine web page for promoting the book. The web page allows you to see the book's TOC and entire Introduction (sans endnotes, alas). And best of all the book is on sale for $45.00.
Might make a nice stocking stuff for your family's resident Thomist. . .