Kanchanaburi city is a practical base for river scenery, the railway and wartime history. The province extends much farther to waterfalls, reservoirs, national parks and the Mon Bridge, so the right plan depends on which part you actually want to reach.
The city sits where the Khwae Noi and Khwae Yai meet and form the Mae Klong. The Bridge on the River Kwai, war cemetery and museums fit naturally with a riverside stay and a rail journey.
Road and rail both connect Kanchanaburi with Bangkok. A city-focused visit can work as a day trip, but staying overnight leaves room for the riverfront after tour groups depart and avoids combining distant attractions into a rushed circuit.
Erawan Waterfall, Sai Yok, Khao Laem, Sangkhlaburi and the Mon Bridge are separate journeys beyond the city. Pick one corridor and check park, road and transport conditions before departure instead of assuming every provincial highlight is nearby.
Two or more nights make more sense when a waterfall or western district is the main purpose. Keep a weather alternative because heavy rain can change trails, water conditions and travel times.