Links
The best known airlines which fly from Amsterdam to Bangkok are: 
Eva air
http://www.evaair.com
China air
http://www.china-airlines.com
These airlines fly almost daily on Bangkok and a ticket costs if you book early approximately 700 euro (return).
A skilful Internet site where you can find several airliners is:
http://www.bmair.nl/Vliegtickets/Azie/Vliegtickets-Thailand-Bangkok.htm
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In Bangkok you arrive on the airport Suvarnabhumi (this airport lies 25 km at the east of Bangkok and is the largest airport in Asia, the passenger terminal and the tower are the largest of the world), this is the airport where all international flights arrive and leave.
To fly to your internal destination (for example Chiang Mai) you can use on Suvarnabhumi :
Air Asia
www.airasia.com
Thai Airways
www.thaiair.com
In practice air Asia will be one of the cheapest.
The old airport Don Muong is now used for all internal flights.
If you want to fly to your internal destination from Don Muong you must nevertheless count on an hour travel time from Suvarnabhumi.
The travel by taxi runs trough the city, it is therefore much more judicious to continue your travelling from Suvarnabhumi.
If you have to travel from Don Muong you can do that with the following airlines:
Air Asia and Thai Airways (see Suvarnabhumi)
Nok air
www.nokair.com
One-Two-Go Airline
www.fly12go.com
All these airlines can be booked by Internet and frequently against cheap prices.
As a rule a return Bangkok-Chiang Mai (1000 km, hour flies) is normally around the 40 euro.
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There are in Chiang Mai a lot of car rent companies.
Our experience is that the most companies are good.
In our opinion the cheapest and best address in Chiang Mai for renting a car is:
www.journeycnx.com
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Some skilful Internet sites with much further information are:
http://thailand.startpagina.nl
http://chiangmai.startpagina.nl
http://thailand.eigenstart.nl
http://hierstartthailand.jouwpagina.nl
http://thailandvakantie.allepaginas.nl/
http://thailand.zoekvinden.nl/
www.maps-thailand.com
www.guidetothailand.com
www.go-chiangmay.com
http://chiangmai.jouwpagina.nl/
http://thailand.startkabel.nl/
A very good Internet site is (on this you can find actual everything in Chiang Mai):
http://www.chiangmaichimes.com
http://thailand.startzoeken.nl/
http://thailand.startgigant.nl/
Holiday rental & Vacation homes