You're probably using the right thesaurus. The default on Apple devices is the Oxford American Writer's Thesaurus, which is great at conveying little shades of meaning. I'm always delighted to find a "Word Notes" entry by an author I like. Try "bourgeois" for Zadie Smith or "feckless" for David Foster Wallace.
(Here's a list of all the word notes by author: http://lasersoptional.com/2012/08/21/it-was-wonderful-marvel...)