To figure out how to spend 30K in Thailand in 11 days, I guess you just have to put yourself in their likely frame of mind.
You've got the wedding dress, which no one but themselves will see. I imagine she would expect that should cost several thousand. Plus if you want to spend hundreds of dollars a night on a hotel in Thailand you certainly can. But even at $500 a night, that still only gets us to $6,000.
For 30K, I don't imagine they are factoring in a first class ticket to Thailand, since those would probably be over 10K each. How frugal of them to choose coach or business ;).
But overall you are certainly right that the number is pretty shocking. I've never been to Southeast Asia, but I imagine that like any other city in the world, they have luxury places that charge Western prices.