By John S. McClenahen Other than being readily recognizable names of U.S. cities, what do Chicago, San Diego, Denver, Austin, and Charlotte have in common? They are the five top target cities for laid-off executives and managers when they look outside their hometowns for new work, indicates Chicago-based Challenger, Gray & Christmas Inc., an international outplacement firm. "From a job seeker's point of view, these cities are perceived to have the most to offer in terms of employment. A major reason for this is that each has retained a diverse industry base and none is merely an automotive or a high-tech town," says John A. Challenger, the firm's CEO. Chicago is cited for its mix of manufacturing, financial services, high-tech, and services. Denver is said to have a good balance between "old economy" and new economy" companies. Climate, ocean, and high-tech companies are major draws for San Diego. Austin is becoming a thriving high-tech community and "its smaller size makes it an easy choice over other Texas cities," says Challenger. Finally, "learning from Atlanta's mistakes, Charlotte is more prepared to handle . . . rapid growth," he states.