I've got two options to go for.
I either arrive in Suvarnabhumi Airport BKK at 00:55 hours and try to catch Train #21 departing at 5:45. Or I arrive (more expensive flight) 15:55 and try to catch Train #67 at 20:30. Both seem cutting it a little close considering customs - and I'm sure #67 I'll run into a lot of traffic.
1. Don't know what early morning traffic is like in BKK.
2. Don't know how long it takes to get form BKK International to the Hua Lamphong Railway Station - I've searched the net and get everywhere from 1hr - 4hrs as a response.
3. The option to catch the train at Don Muang seems like a good idea if I order my ticket before hand and have it mailed to me. How long to there from the airport? Is this an easy option for someone without a lick of Thai?
I know I have the option to just stay a night or two in BKK but I'd rather not as I'm going to do that when I come back for my return flight.
First up Thai customs and immigration.I take it your not familiar with Suvarnnabhumi.From your arrival to immigration hall there are moving ramps which mean you can move pretty fast.There's usually a long queue at the immigration but don't be perturbed move on another 50 metres or so and you'll find another line of immigration booths probably a lot quieter.Immigration is usually very smooth and takes but a few minutes just in time to find your luggage is already on the carousel.If you take a taxi(ignore all the touts) it will take you no more than one hour to get to Hualamphong at night even if you miss out on the expressway.Early morning traffic in Bangkok is always really bad so even going on the expressway the taxi will, at the end of the journey approaching Hualamphong, be stuck in heavy traffic.I believe the rail-link is running now but only runs from 6:00am to midnight so that would be a better option for the afternoon flight.It takes you to Payathai where you can change to the metro going to Hualamphong.
If it was my call I'd arrive at 00:55.Nice and quiet.Easy to find a taxi and Bangkok is a 24 hour city so when you arrive at Hualamphong you could probably find somewhere selling coffee and wait for your train.
Getting from suvannabhumi to Don Muang.There is a bus link and a taxi would go on the expressway out of the city but it seems a long way to go, probably near to 2 hours.
You don't seem to have a ticket so be aware that 2nd class might be fully booked on the same day but probably not.You'd want to avoid 3rd class if you're tired and have a long journey but fine for short ones.Good luck.
"I either arrive in Suvarnabhumi Airport BKK at 00:55 hours and try to catch Train #21 departing at 5:45. Or I arrive (more expensive flight) 15:55 and try to catch Train #67 at 20:30. Both seem cutting it a little close considering customs - and I'm sure #67 I'll run into a lot of traffic."
To me 00:55 (0055) means 55 minutes after midnight. I have never passed through Thai immigration that took several hours to complete! If your intention is to arrive before 1 a.m. and catch the 05:45 (0545) morning train you can do it easily. Unless one of us has the times mixed up. From 1 a.m. to 5 a.m. is plenty of time to finish with immigration and take a taxi to the train station. Most of the time I am in and out of immigration before my bags come off the carousel.
Meter taxi from the airport to Hulamphong Train Station definitely less than hour unless some truly strange traffic condition comes up. Most taxi drivers know ahead of time what the road is like ahead and avoid many potential problems.
Which airport are you arriving at? BKK is Suvarnabhumi and Don Muang is DMK.
I know you want to blow off Bangkok for one night but consider this. You arrive at either airport and stay the night in a hotel and then at your leisure meet either train departure. In the city during the day hours the Skytrain connects with the subway, the subway goes right to the national train station. If you are coming from a long distance wouldn't you want to take a shower anyway?
I always prefer to arrive during day hours. You get a full night in a hotel and cheaper transportation is easier to get. The new Rail Link goes right to the Pratunam area. The City Line only costs 15 baht until the end of December. From the last stop at Phaya Thai you could even switch to the Skytrain for hotels or even connect with the subway. There is a subway connection at Makkasan but there is also some construction in that area too. Eventually I think there will be some sort of moving conveyor belt to transport passenger closer to the subway connection. At present no Skytrain or Rail Link after midnight.
If your plane arrived early and you was able to grab the Rail Link to the Pratunam area a meter taxi to a hotel or even to the train station is very reasonable. During the day hours there is an Airport Express Bus that also has a stop near the train station.
You will have to change money over at the airport, there are bank money changers available 24 hours a day. Get small bills and even some change for taking taxi rides. There is a cheap food court (Magic Food Court) on the first floor near the Airport Express Bus kiosk. That food court is the cheapest place to eat at at the airport and open 24 hours a day.
Up to you.