Seniors are generally well respected in South Korea. People usually offer their seats to older people and help elders with their bags. As Koreans are dealing with a rapidly aging population, the government is offering discounts to seniors (ages 65 and older), such as lower rates on public transportation and discounted (or even free) entry fees to tourist attractions. You'll need to show your passport or other form of identification showing your age.
Many reliable agencies and organizations target the 50-plus market. Elderhostel (tel. 800/454-5768; www.elderhostel.org) arranges worldwide study programs for those ages 55 and over.