The word sprightlier is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 19
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (28 words)
girlier, girlies, girlish, glister, gripers, grister, gristle, lighter, philter, philtre, piglets, pithier, pitiers, plights, regrips, relight, resight, resplit, righter, sighter, siltier, sleight, slither, spright, striper, tigrish, tipsier, triples