U.S. citizens can visit South Korea without a visa and stay for up to 90 days with just their passport. With the optional K-ETA, they can avoid completing an arrival card.
From April 1, 2023, to December 31, 2024, the Korean Electronic Travel Authorization (K-ETA) is not required for US citizens for stays of 90 days or less that are for tourism or business purposes. Visa required for all other purposes, including employment, teaching English, and for stays longer than 90 days.
In short, you can't go wrong flying either Asiana or Korean Air. Both airline programs offer valuable award charts, although Korean Air is devaluing its partner award chart in April 2023. However, Korean Air does offer a superior route network and travel credit cards to U.S. travelers.
Travelers arriving in Korea are unable to carry animal products (such as meats, dairy, eggs, etc.) or plant products (such as fresh fruits, seeds, etc.)into the country. In-flight meals which include the aforementioned items, cannot be taken off the aircraft upon arrival.