Watch out for RBC. It might sound like it's free, but it's not! Here's their strategy, which will only be revealed to you as you start processing the transaction:
they convert your funds from CAD to USD at a horrible rate
they transfer USD to your Thai bank, where you may or may not be subject to a bad/decent/fair rate
That first step means that you effectively lose 2.5% (or more), so there are a bunch of better ways than RBC.
Not as popular here as some methods, but I use XE.com, which gives a very fair conversion directly to THB and charges no additional fees. They link directly to your bank account if you set it up that way. They're a little slower than some other methods (usually a week from start to finish).
I cannot speak to the implications of the money arriving to your bank in THB, which is how XE delivers.
Ultimately, my advice is just to avoid RBC. They suck.