Benchmarked strictly across TripTiming's 5 empirical pillars: Crowds, Weather, Vibes, Prices, and Safety.
Tokyo emerges as the optimal September destination with an overall TripTiming Index of 57/100 vs 54/100 for Seoul (+3 point advantage). Tokyo delivers a decisive lodging value advantage (~$218/night vs ~$224/night in Seoul, saving ~$42 across a 7-night stay). Sightseeing is further aided by comfortable outdoor weather (33°C feels-like). While Seoul retains an edge in City Vitality (62/100 vs 57/100), Tokyo's commanding performance in Price & Value secures the overall September recommendation.