Vacations were short and simple for Mary Kay Conlon and Chip Plumb in their fast-track corporate days. "One phone call, no planning, never more than a week," says Conlon. "We'd just plop on the beach somewhere." But to celebrate their early retirement last year, the Evanston, Ill., couple rented a spacious Paris apartment for six months. "We always regretted that neither of us had done a junior year abroad," says Conlon, 48, a former health-care-industry executive who was eager to immerse herself in another language and culture.
Shopping in local markets, picnicking in the Luxembourg Gardens and jogging around the nearby...