Are taxis safe in Bangkok

Taking a meter taxi is pretty safe for Thailand. No worse than New York, London, Frankfurt, etc. Except that it is cheaper!

I would avoiding getting a taxi dropping off at departures - you only save 50 baht that way anyway!

The meter taxis are regulated pretty good if you get them from the meter taxi sign up desk, first floor, near the curb. There are two locations, if one is full of tourists just move on down to the next section and see if your line moves faster.
http://www.bangkokairportonline.com/node/52

On floor 1 (not far from the Airport Express kiosk) is the Magic Food Court, the cheapest place to eat at the airport.

Look for a blue colored podium style desk, there is a picture of a taxi on it and it says "Public Taxi." The desk clerk will ask you where you are going, tell the driver in Thai, write that destination down on a receipt. Keep the receipt! The receipt tells you how to complain about a bad driver, etc. You pay the surcharge of 50 baht and meter fare at the destination (hotel or for you bus station.) You pay any tolls during the ride. Have small bills available, it is not a rip-off if you are too stupid to have small bills and change and the driver can't change a 500 baht note! (Some drivers claim to not have any change anyway, they hope the tourist is dumb enough to say "keep the change!") Meter starts at 35 baht, make sure that nothing is blocking the meter.

I keep my bag with me on the back seat. If I have to bail out quickly or strangle the taxi driver I don't have to go in the trunk to get a bag! It is normal for the driver to ask for toll money during the ride. Prices are clearly posted. Meter taxi desk clerks are supposed to verify that the taxis are safe and record the serial numbers of the taxis.

One trick I saw women using when taking a taxi alone is to use their cell phone to photograph the taxi and driver and then having the photo sent to a friend. If the driver sees her photographing his taxi and face he knows that his photo will be on TV or in the newspapers if he does something wrong. Or, the woman can just fake it by pretending to take a photo of the guy, etc.

Anytime you bargain the taxi fare in Bangkok you pay more! Meter charges are cheaper and fair. No need to tip a lot either! If you want to round off the fare and get rid of some coins go ahead but is not necessary.

Good luck.