David and Lisabeth Sewell McCann of Charlotte have found a way to make family vacations more fun. The founders of Sparkle Stories, an online audio storytelling service, recently released Martin & Sylvia "Travel!" Audio Book. The two-hour-long title includes five tales featuring two of Sparkle Stories' most popular characters: brother-and-sister duo Martin and Sylvia. They're on a trip with their family, and they play games and find ways to entertain themselves on the journey. David Sewell McCann thinks little listeners will get the hint because, he says, "it's not a lecture, it's not a how-to, it's just a story." The price of the audio book includes real instructions for the games fictional Martin and Sylvia play.