The Work Loft is in the centre of the city and have MRT nearby. They have nice filter coffee and best part is they are open all day 24hrs.
Suvarnabhumi Airport- get a sim before you leave the terminal, After the Customs Booths, turn left for Cell Phone SIMs. You'll find booths for DTAC and AIS at gate 7. They will have various options ranging from 200-800 baht
For cabs make sure to have them run the meter, they are required to turn it on by law, get out if not. Uber is working fine for me (although a legal grey area in bangkok), the app "Grab" works great as well and appears to be about 30% cheaper.
Great cafe to work with comfortable seating. It is quiet cafe that has students studying as well. The best part is that it has a decent WiFi and is open 24x7.
A well priced co-working space at 200 THB for 3 hours or 300 THB a day. They have a meeting room, a snack bar, library, a printer and awesome WiFi. The place has a great vibe with some community events taking place on a weekly basis.
The Hive has a massive 6 floor space in Bangkok with hot desks and meeting rooms. They have a rooftop cafe with a garden as well. The lounge area is nice to have meetings. Lots of startups are running out of this space.
A bungalow converted in to a co-working space. Love their events and they have both indoor and outdoor tables to work on. Good internet and places around to eat.