United Airlines, the country's second-most profitable carrier after Delta Air Lines, has unveiled new cabin designs, including on some of its smallest planes, that feature more premium seating options and fewer in standard coach. The airline is making another investment in Denver, purchasing 113 acres outside the airport where it has a key hub. The new designs include a more premium-oriented subfleet of narrow-body Airbus A321neo jets for transcontinental flights with 20 Polaris seats, which can recline into a bed, and 36 extra legroom seats. Despite a recent surge in fuel prices, United Airlines executives have maintained strong demand, with premium-travel demand outpacing the main cabin.