Bangkok Taxi's charge by time and by kilometre. There really isn't a fixed rate per distance. travelling 3KM during heavy traffic will cost more than the same route during light traffic.
If you have an eVisa you will need a print-out of that. I didn't see that in any of the paperwork requirements and I showed up, waited 1.5 hours, then they told me to come back.
If you are coming from the US.. Licorice and Google Voice.
If you travel anywhere, including Thailand. Try to be respectful of the local people and their cultures. 95% of the people on this site that have problems, have problems related to not having proper respect. It's not difficult..
, additionally, if I had to do it all over again, I would book directly from the hotel AND I would get a reference from this group, a hotel somebody has had a good experience.
When I booked I went through Agoda. ThaiPass, Agoda, and hotel was a nightmare situation, I dont recommend it.