Bangkok is a vast city, offering hundreds of sightseeing delights to its visitors. Getting about in such a city would have been a daily headache and certainly very time-consuming, were it not for the BTS skytrain public transport system that gives the traveler quick and comfortable access to the wonders that Bangkok has to offer.
There are two main lines that the BTS services, the Sukhumvit line, which brings you to places like the huge MBK Mall, the Jim Thompson museum, the Erawan Shrine and the Pratunam wholesale market, and the Silom line, which gives you easy access to, among others, the airport train, China Town and the Chatuchak Weekend Market.
Each BTS station is staffed with friendly, English-speaking ticket sellers as well as security guards. The trains are on time, clean and air-conditioned, and run very quietly and comfortably. The next station coming up is announced at regular intervals in both Thai and English on the trains, and the train ticket also has a little map of both lines with the names of the stations along the lines clearly printed, so you always know exactly where you are. My personal experience of the BTS skytrains has been that it brings you quickly, efficiently and comfortably to your destination, while offering panoramic views of the city on the way.
I've been going to Bangkok regularly for the past 20 years and what a difference the Skytrain has made to getting around the place - especially since they extended the line down past the river. It's always clean and you feel safe and it's really inexpensive. Best way to get around the city to the major points.