For many economy flyers, the best long-haul sleep hack is simply lucking out with a row to themselves. A handful of airlines are betting some will pay to guarantee it. United Airlines recently made headlines for its upcoming "Relax Row" — a set of three economy seats with legrests that flip up to create a fully flat bed-like space. It's designed to give budget-conscious travelers a taste of business class without the high price tag. The move fits into the airline's broader push toward premium