There's nothing more nostalgia-inducing than a trip down memory lane with your taste buds. Your long-ago visits to classic restaurant chains with family and friends surely produced many indulgent memories: the mac-and-cheese at Howard Johnson's, the happy hours at Bennigan's, the crepes at once-trendy The Magic Pan.

Alas, changing times and tastes of aging boomers have helped spirit away many of those establishments. "Every day boomers are leaving the market" - in other words, passing away, says Alex M. Susskind, professor of Food & Beverage Management at Cornell University's School of Hotel Administration. "Even if chains can still appeal to that demographic, it is shrinking. I would also argue that boomers' tastes are changing, and what appealed to them when they were younger, single and/or raising their families is not the same."

That's fair warning to today's crop of popular restaurant chains (and affiliated suppliers and investors), which may soon feel the heat of the shifting tastes and loyalties of Gen X and millennials. "Younger consumers are loath to sit in a restaurant for an hour, unless it is really something special," Susskind says. "Under the best of circumstances, a meal at Applebee's or Friday's takes about an hour." Younger consumers are "more interested in quality and are willing to pay for it -- eat out less, but better. They are more interested in sustainability, and they love delivery and takeout."

Consider the changing trends and operational missteps that led to the retreat or outright demise of these 14 classic chains:

Howard Johnson's

Courtesy Ben Schumin | CC BY-SA 3.0

What took the mojo out of HoJo? In the 1950s and '60s, Howard Johnson's restaurants were a real roadside attraction for baby-boomer kids being carted around in the car by their