The best option is the 12Go bus, ideal for those willing to endure a longer ride for a reasonable price. Be prepared for the extended travel time.
Traveling from Phang Nga to Koh Samui involves a bus journey taking about 360 minutes. Given the length of the trip, it's important to assess if this suits your plans. Currently, the only available option is by bus.
The cheapest option is a bus ride costing between 450 to 900 THB. However, keep in mind that the journey takes around 6 hours.
For families seeking comfort, the bus might be less ideal due to the lengthy travel time. Consider if the comfort level aligns with your family's needs.