An effective way to move around the city of Bangkok is by boat. The metro is modern and sophisticated but the river boats are... well... watch the video.
Everybody seems to enjoy the boats a lot because they are so characteristic. I used them several times during my stay in Bangkok for Steem Fest 4 and I loved the experience. If you happen to go to Bangkok, make sure you try the river boats. It will make you feel like a local. Have fun!