Most of us reading (or writing) Grandma's Briefs are grandparents. Which means most of us here know how much money grandparents spend on their grandchildren, their parents, their children and, when there's a smidgen left, on ourselves.

Interestingly, marketers don't seem to know how much we grandparents spend on ourselves and our loved ones. Or so it seems. Perhaps they do know—some brands clearly do—though they have yet to figure out how to effectively reach us with messages on the services and products we want to see, want to use, want to buy.

Author Lori K. Bitter lends them a hand in her new book on the topic, The Grandparent Economy: How Baby Boomers Are Bridging the Generation Gap ($34.95, Paramount Market Publishing), which I recently received free for review.

The 138-page primer on engaging the 65 million grandparents in the United States is a must-read for marketers. And, thanks to all the graphs and stats and tidbits Bitter provides on...