Luxair, Oman Air and Bangkok Airways are offering cheap double open-jaw flights from Europe to Thailand!
Fly from Luxembourg or Amsterdam to Bangkok with return from Koh Samui to London, Munich, Milan or Zurich from just €274.  You must start in Luxembourg  or Amsterdam to get that price. One checked baggage (20 kg) and one cabin bag per passenger is allowed.
We found available date for this price in November 2017.  Go: 5.11. back 25.11.17
Example dates: 7-7-8-27 May, 11-11-12-24 Jun, 3-3-4-23 Sep, 29-29-30 Oct – 18 Nov, 5-5-6-25 Nov
Also possible:
Amsterdam – Bangkok & Koh Samui – Munich:  for € 310.
or:
Luxembourg – Bangkok & Koh Samui – London: for € 306
or:
Luxembourg – Bangkok & Koh Samui – Milan: for 309

Example:


To get that fare, insert in the multistop (Gabelflug) Momondo search your travel dates:

Hotels in Koh Samui: