Whether it's a good idea depends heavily on your total layover time and legal status. For domestic flights, experts recommend at least 4–6 hours to account for deplaning, travel to the city, and re-clearing security. On international layovers, you should have at least 8 hours because you must pass through immigration and customs twice—once to leave and once to return—which can be unpredictable. You also need to verify if you require a transit or tourist visa. While leaving can break up a long trip and let you see a new city, it adds stress and extra costs like transportation and meals. Always work backward from your boarding time, not your departure time, and ensure you have a "Plan B" in case traffic or long lines at security put your connection at risk.