Took my bike to Thailand via BKK airport last January. No big problems at customs (I was accompanied by a thai-speaking person, which of course did help a lot!) and took us about 2-3 hours to get the bike out of there. There´s a free shuttle bus going from the main passenger terminal to the cargo area (the airport is BIG!)
The important paper will be the T2 temporary import paper (not sure if I remember its name 100% correct), where it is stated, in Thai and in English, that if you fail to re-export the vehicle within 30 days, you face paying in taxes and duties a ridiculous amount of baht (our bike was worth maybe 7000 euros, and this sum equalled some 24.000 euros!)
I hear you are able to work your way around this, or at least some people do so, and then they are able to keep it in Thailand for about 6 months or so. Or you can visit a neighbouring country, and get new 30 days. We stayed only a couple of weeks, so for us it was never an issue.