My question is: Do they actually want to go to Thailand? Have they ever expressed any interest in traveling long hours on a plane to visit there? A gift should be for the benefit and pleasure of the recipient. If they have no desire to go there (or anywhere they may feel uncomfortable), it's not really a gift designed for them, is it?

Why not ask them where they want to go on a honeymoon, and then give them that? Even if they say Cancun or Branson. It's their honeymoon, they should have some say.

If they were experienced travelers that have always wanted to go, or go back, to Thailand then that would be different. Many people find foreign travel stressful not not very fun. To each their own.