Arrival

For reasons unknown, I consistently found upon arrival that the immigration station on the left (if you are standing facing immigration to go out to baggage claim - I think it is station #2) is usually packed, with extremely long lines, and every time this is so, a short walk down to the other station finds very short lines of 4 to 8 people.

Take note of this if you arrive on the side of the airport where the left-hand station is the first one you encounter after getting off your plane. If you're like me, you despise standing in line at immigration.
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The airport train is now in full operation. The express train to Makkasan station is 150 baht, and it takes 15 minutes. The local train is 45 baht to Phaya Thai station where it connects with the Skytrain, and takes 30 minutes. I experimented with a variety of strategies, and ultimately settled on the local train to Phaya Thai, transfer to the Skytrain, then take that to Nana Station.

Of course you can still take a cab too, if you arrive during the time of day when the traffic isn’t too bad on the toll way or the city streets – which usually means really late at night. Most of the time the toll way is pretty clear. It’s when you exit and hit the city streets that gridlock appears. I loathe sitting in traffic, so I opt to take the trains to Nana.

Please note that if you take the express train to Makkasan station and opt to take a cab from there, getting out of the station and going in the right direction can be a challenge. In one of the many moments of brilliance in Thai planning, they forgot to put in traffic lights at the end exit. So essentially vehicles are forced to go one way – and that would be away from Sukhumvit, not toward it.

Departure

They were experimenting with implementing a “single line, take the next available agent” set up with the passport control station on the right. However, when I went through for my final departure, both sides were back to the old “pick a line and hope it goes fast” system.

It all depends on how many flights have just landed as far as the lines for immigration go, in December I landed just as a flight full of Russians landed, and I was on a full flight from Japan.

On the 4th I got through immigration before my bag made it to the baggage area. I think it's just a hit and miss thing.

If you want to take a chance just go onto the far immigration area and jump in the diplomatic line, and then lie about why your there. What I told them was that a employee had told me to use this line because of the large group of people at the other counters. YMMV using this shortcut.