There are a few options to get to BKK if you're willing to go indirect: via DEL/BOM with Jet Airways, BAH with GF, CPH with SAS or KUL with Malaysian.
Koh Samui is probably more tricky.
Edit: Malaysian codeshares with Bangkok Airways so you may be able to get to Koh Samui in one stop via KUL although I imagine you may not be allowed to redeem VS miles on a codeshare.
Last edited by BA304; May 24, 2012 at 9:50 am
Reason: Incorrect airport code