I think everyone is extremely impressed with the rapid transit system in and around Bangkok. Its all fairly new. Here’s a description to help you understand the map below. BTS Skytrain is the elevated train system with 2 lines. The Silom Line and the Sukhumvit Line. These two lines intersect at the Siam Station. Lots of shopping around Siam and lots of hotels too. We find the a average ride on the Skytrain is about .50 cents or 15 Thai Baht.
The MRT system you see on the map below is a below ground subway system. Its a different kind of train than the Skytrain and yes these 2 lines intersect. On the Sukhumvit BTS Skytrain Line at the Asoke Station where the new Terminal 21 mall is, you can transfer from the Skytrain to the MRT Subway System. On the Silom Skytrain Line, you can transfer at the Saladeng Station to the MRT Subway system. So you do not need to rent a car in Bangkok.
Rapid transit ends at midnight so you’ll be taking a taxi home from your night out, but traffic is easy at 1am. The newest train is called the Airport Link. Its an elevated train system and as the name implies it goes to the international airport. This line intersects with the Bangkok Transit System (BTS) Skytrain at PhayaThai Station. From here you are good to go anywhere in downtown central Bangkok! So when you arrive at the Bangkok Airport, you do not need to take a taxi to your hotel, you can take the Airport Link and transfer to the Skytrain. Its easy with minimal walking and you never leave the stations when you transfer!