Southwest Airlines is shaking up its famously simple no-frills model with a new aircraft design that promises a more "elevated" flying experience, with similar upgrades planned for its existing fleet. The Dallas-based carrier unveiled its first Boeing 737 MAX 8 with a refreshed interior this week — complete with an extra-legroom section, new high-end seats and refreshed lighting — underscoring the company’s broader push to modernize its fleet and offer new perks to customers.The new aircraft, which enters s ...