The best option to reach here is by train. It cheap and comfortable. However, if you miss the train there are buses in every one hour that will take you there. The last and the most expensive option is car. Train is about 40 baht and bus will take you to Kanchanaburi for just 150 bahts. Kanchanaburi is a very small and beautiful town. There are a few tourist attractions that worth exploring. Like the Erawan waterfall, the war cemetery, the tiger temple and the bridge over the river Kwae. If you want a little more adventure, don't stay in town area of Kanchanaburi. Take a bus from the Kanchanaburi station and go to Erawaan. Is a small town/ village with really amazing landscapes. It's about an hour away, but it's worth every penne spent. We stayed in a small bamboo house in the middle of the Forest called the 'shanti farm'. It was a lovely experience, there is no electricity or internet here. The bulbs work on solar panel. The hosts are really god people and the hostess is a great cook. If you want to cut yourself off for few days, this place is all you need. They can arrange for bikes as well. The places to see here are Erawan waterfall. Great place to swim and click some photos. You can visit you national park as well. There Is a Dam and a cave that can be visited as well. All really close by. The entry ticket is about 300 bahts per person. On your way back to Kanchanaburi, you have to visit the tiger temple. It is a great experience to feed the Tigers. Make sure you reach there before 2.30pm least as they stop giving out tickets after 3pm. Don't wear pink, red, yellow colours. Best is to wear whites. The ticket is 300 bahts. For feeding the Cubs it's 1000 bahts per person and it's a 45min session. You can explore the bridge and the cemetery as well. It's a great place to explore while on Bangkok, after all the shopping and bar hopping. This place will surely calm you and make you feel relaxed and will definitely make you see the other side of Thailand. You can take a bus back to Bangkok. That would be the best option. Have a nice trip!