If you would like to travel by bus in Bangkok, the website Transit Bangkok can help figure how to get from Point A to B via bus and also sky train, subway, and boat taxi. Although not completely flawless, Transit Bangkok can lead you in the right direction and make navigating the Bangkok transportation system much easier.
You might also want to try the Bangkok Mass Transit Authority
Types of Buses and Fares (Bangkok)
Taking Buses Throughout Thailand
To take buses throughout Thailand, depart from one of three terminals in Bangkok; Ekkamai (Eastern), Mor Chit (Northern), or Sai Tai Talingchan (Southern).
For bus timetables CLICK HERE
Ekkamai Terminal - to Pattaya, Rayong, Koh Samet, and Koh Chang+++
The Eastern terminal is located on Sukhumvit Road and Ekkamai, adjacent to the Ekkamai Sky Train exit.
Mor Chit Terminal - Chiang Mai, Chiang Rai, Nong Khai+++
Take a taxi direct to Mor Chit or take the skytrain to the Mor Chit station and then take a taxi to the terminal. Walking is not really a viable option.
Sai Tai Talingchan - Hua Hin, Phuket, Ko Samui, Krabi, Phuket, and Kanchanaburi+++
The most convenient method of reaching the southern terminal is via taxi.